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Bio-Fluorescence Night Dives

also known as

Glow-Dives or Fluoro-Dives or Fluo-Diving


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What is "Fluo-Diving" and why would you want to make a "Fluo-Dive"?

A video is worth more than a thousand words:

In short:

WHAT: Night dives with an ultraviolet torch for viewing bio-fluorescence, the property of some marine life to re-emit light with a longer wavelength (of visible light) when lighted with (invisible) ultraviolet light.

WHY: Because the sight is magical, enchanting - as if the underwater life was actively shining like neon signs in the dark, or like a psychedelic disco, in many different colours. It is discovering a hidden world behind a hidden world.

Long explanation:


Many marine organisms (for instance corals, tunicates, barnacles, sponges, anemones, jellyfish, clams, nudibranchs, cephalopods, shrimp, crabs, worms, fish) produce proteins which have the property to react to certain wavelengths of light with a phenomenon which is called "fluorescence".

Fluorescence is the effect that the electrons of certain materials, in this case proteins (but there are other materials which also have this property, certain minerals for instance), absorb the photons of a certain wavelength of light, by which the electrons get "excited", i.e., promoted to a higher energy level. After a few nanoseconds, these electrons fall back to their initial energy level by emitting another photon of light, however with a longer wavelength (i.e., with a lower energy) than the exciting light.

In the case of marine life, the exciting light can have wavelengths in a wide range between (invisible) ultraviolet and (visible) blue, and the wavelengths of the emitted light are usually blue, green, orange and red, depending on the specific protein the organism produces.

Note that fluorescence is different from phosphorescence (after excitation, light is emitted over a longer period of time, as can be seen e.g. in cathode ray tubes, i.e., in pre-digital age television sets) and from luminescence (some marine organisms actively produce their own light using certain enzymes or symbiotic bacteria).


Some fluorescent corals have been discovered because they were bright red despite the fact that at the depth that they were found, red light is completely absent, because red light is the first to be filtered out by water (which is also the reason why water appears blue from above, and why underwater images have such a blue tint, unless corrected).

When divers first dived with torches under water, they discovered that many organisms were actually red. It was a biological mystery why organisms would spend energy to produce a pigment which would appear black below a certain depth anyway. It was speculated that this was used for hiding, but this hypothesis was not very satisfying.

New results from scientific research show that many fish, even deep see fish, can actually see red light. One wonders why, since there is no red light at these depths.

It has been found recently that underwater organisms actually use fluorescence to transform the only light available to them, namely ultraviolet and blue light, into visible light of longer wavelengths, such as red (of all colours!), among others, for a number of purposes:

Besides from protecting themselves from the harmful effects of ultraviolet radiation, as a kind of sunscreen, corals seem to do this in order to feed their symbiotic algae, which live inside their tissues. This allows the corals to dwell at greater depths, where corals without this capability are unable to thrive.

Recent discoveries seem to suggest that fish also use fluorescence, in order not to be easily discernible from the background of fluorescing corals, which otherwise would make them easy prey, and in order to communicate between each other (within the same species), at least at short distances.


The capability of marine organisms to fluoresce was first discovered in 1927, as far as we know [1], by a certain Mr. Charles E.S. Phillips, at the beach of Torbay, England. He noticed some anemones in a tidal pool which had a particularly bright green colour. He took some samples to his laboratory and examined them with the help of a light source and a filter called „Wood's Glass“ [2], which absorbs visible light and only lets UV light pass through, and thereby proved that these anemones were in fact fluorescent.

In the 1930s the Japanese marine biologist Siro Kawaguti examined the pigments of corals and discovered that the most common pigment fluoresced in green.

In the 1950s divers started to explore fluorescence under water:

In 1951-1961 Dr. Richard G. Woodbridge III built some underwater blacklight torches and wrote articles in „Skin Diver“ magazine in 1959 and 1961, and also in „Nature“ in 1959, about his discoveries in the cold waters of the Atlantic near the coast of Maine.

Luis Marden, a photographer for National Geographic magazine, reported in 1956 that he had found red anemones at a depth of 18 meters (60 feet), although there should not have been any red light at that depth. The red colour disappeared in flash photographs, and Marden concluded correctly that the effect was due to fluorescence. Fig. 1 shows such a red anemone at the same depth.

[Fig. 1]
Fig. 1 - Red fluorescing anemone during daylight at 18 meters (60 feet)

In 1963 Sir Arthur C. Clarke [3], a renowned science fiction author and diver, bought some fluorescence torches from Dr. Richard G. Woodbridge III and described his experiences with them for instance in his SF novel „Dolphin Island“ [4].

[Delphininsel Cover]    [Dolphin Island Cover]
(Click on the images above to see the respective pages of interest)

In 1955 the fluorescent pigment later baptised „Green Fluorescent Protein“ (GFP) was first described and recognised as a protein. In 1962 GFP was extracted from 10.000 jellyfish of the species „Aequorea victoria“. In 2008 Osamu Shimomura, Martin Chalfie and Roger Tsien, who had worked independently in this field, jointly received the Nobel Prize in chemistry „for the discovery and development of the green fluorescent protein, GFP“ [5].

GFP and its variants (they exist in all colours of the rainbow, nowadays) have many applications in molecular biology, genetics and medicine. In reproductive medicine for instance there is a method called „Fluorescence In-Situ Hybridization“ (or FISH for short, coincidentally), which allows to detect missing or surplus chromosomes in embryos (so-called „aneuploidies“ such as Trisomy 21 or „Down Syndrome“) in what is called pre-implantation genetic diagnostics or PGD.

In 1959 Rene Catala, Director of the Noumea Aquarium in New Caledonia, was the first to systematically test corals for fluorescence with UV light in his aquarium. He built displays with fluorescent corals at his own aquarium as well as in Antwerp, Belgium. Aquarium displays of fluorescent corals using what is known as „actinic lighting“ have been an indispensable attraction ever since, both in zoos all over the world as well as among amateur fish and reef tank owners.

In the 1970s Dr. Charles H. Mazel started to conduct scientific research in the area of underwater fluorescence. In one - rather unusual - project he investigated how to allow Navy divers to see under water at night without being seen from the surface, with the help of strong UV torches. Unfortunately this did not work out as expected, because of the fluorescence of omnipresent organic matter dissolved in the water (mostly fulvic and humic acids from decaying organic matter, runoff from land, etc.). It should be noted by the way that silt will generally not fluoresce to any significant degree. Dr. Mazel wrote: „There was a very weak visible glow from water itself (not the dissolved components) that comes from Raman scattering. This is not fluorescence and in itself would not produce the kind of distinct »water-glow« you show in your excellent photo. Rather, it would be a very weak purple, not visible from much of a distance“. See „The inherent visible light signature of an intense underwater ultraviolet light source due to combined Raman and fluorescence effects“ [10] for details, and see Fig. 2 below.

[Fig. 2]
Fig. 2 - Intense UV-A light beam under water (365 nm)

By measuring excitation and emission spectrographs, Dr. Mazel discovered about 1990-1992 that contrary to standard practise and common belief (which inseparably associated ultraviolet light to fluorescence) ultraviolet light was not the most effective wavelength for stimulating fluorescence in GFP, but blue light was, of about 450-470 nm wavelength. Based on these findings Dr. Mazel subsequently developed the modern form of fluo diving with blue light torches and yellow filters [7].

In 1999 he founded NightSea in order to make this technology available, not only to enthusiasts and research institutes, but also to industry e.g. for Non-Destructive Testing or NDT (BlueLine NDT).

Starting in 2007 Prof. Dr. Horst A. Grunz was the first to build „HiTec fluorescence torches“ using blue high power LEDs, based on the principles established by Dr. Mazel, which torches allow to illuminate a bigger section of a coral reef at once (see for instance DiveMaster Nr. 64 issue 2010/02 p. 17-22 and [8] [9] [10]). This is of special interest in the scope of efforts to protect coral reefs. See also Figs. 3-5 below (used with kind permission).

[Fig. 3]
Fig. 3 - Prof. Dr. Grunz's original HiTec fluorescence torch with four quadruple Osram high power blue LEDs

[Fig. 5]
Fig. 5 - Prof. Dr. Grunz's fluorescence torch with four Cree XR-E blue LEDs (used with kind permission from DiveInside)

[Fig. 4]
Fig. 4 - Prof. Dr. Grunz's „Hawaii“ HiTec fluorescence torch with three Luminus SST-90 blue LEDs

Inspired by Sir Arthur C. Clarke's SF novel „Dolphin Island“ [4], in autumn of 2010 the author began building his own fluorescence torches, because he could not find any commercially available UV dive lights. In order to get as close to the experience described in that book, initially the author exclusively used UV LEDs and built torches of increasing power, first with a single LED of about 395-410 nm and 1 Watt, then a torch with two LEDs from market leader Nichia with 365 nm and about 6 Watt, and finally a torch with 4 quadruple LEDs (equivalent to 16 single LEDs) from Nichia with 365 nm and together about 46 Watt. Later on the author also bought and built blue light torches with up to 90 Watt. See further below on this page for the details.

Together with the dive instructor and physicist Lynn Miner, the author founded in May 2012, in order to be able to offer high quality yet affordable equipment for fluo diving, in order to lower the entry barrier to this unique and overwhelming experience.

For more details, see History of the Discovery of Marine Fluorescence (CharlesMazel@NightSea).

For another historical document, see also Photographing Fluorescent Corals (PDF 663KB) (Jack&SueDrafahl@SkinDiver).

UV versus Blue:

Ultraviolet versus blue excitation light for fluorescence:

As demonstrated by Dr. Charles Mazel, ultraviolet light is about four times less efficient to excite fluorescence in Green Fluorescent Protein (GFP) than blue light of equal energy; see the second chart on his page Why NIGHTSEA uses blue light for underwater fluorescence for illustration.

Another aspect to consider is the fact that ultraviolet light emitting diodes (LEDs) are MUCH more expensive than blue LEDs (by about a factor of four, for the same nominal electrical power, in Watt), and MUCH less efficient, in terms of light output or "radiant flux" (also by roughly a factor of four, measured in Watt or milli-Watt).

This means that an ultraviolet LED is about 16 times less efficient to excite fluorescence in GFP than a blue LED of equal nominal electrical power, for about 4 times the price.

In other words, it would cost you about 64 times more to obtain the same results with UV LEDs as those obtained with blue LEDs.

Note that depending on the characteristics of the fluorescent pigments to be excited, such as pigments which fluoresce in red, still longer wavelengths of light, such as in the green range of the spectrum, may be needed in order to excite their fluorescence most effectively. But then you will only see red fluorescence, and no other fluorescent colours.

Blue light is therefore the best solution in order to see the most fluorescent colours with the highest efficiency.

The advantage of ultraviolet light (as opposed to blue light), that no filters are needed, is outweighed by the fact that shining powerful UV radiation into your eyes (or your buddy's) may cause severe harm to your or your buddy's eyesight, especially because this radiation is invisible and therefore the corneal reflex (blink reflex) and the pupillary reflex do not work.

Strong blue light (as any strong light) can also cause damages, by the way, but since you will immediately feel a strong discomfort this is somewhat less likely to occur.

Research into the effects of UV or blue light on marine life is still outstanding. It is known that light at night in general may disrupt the circadian rhythm of sleeping animals, or may even disrupt their reproductive cycles. Parrot fish for instance produce a "sleeping bag" made of mucus. If woken up and caused to flee, they will not be able to produce another one and will spend the rest of the night unprotected from predators. Direct damage from the strong light of the torches is a suspected possibility, but it is believed that the energies involved are much lower than those of the ultraviolet and blue radiation from the sun during the day, especially when considering the usually very short times of exposure of a few seconds, or at most a few minutes.

You can see the difference between UV and blue excitation light in the following videos: (6:48, UV 365 nm), (2:44, UV 365 nm), (9:11, blue 450 nm).

The torch used for the first two videos had about 46 W nominal electrical power, and used 4 Nichia NC4U133A UV LEDs (corresponding to 16 individual LEDs).

The torches used for the third video had 21 Luxeon Rebel, 3 Luminus SST-90 and 18 Cree XT-E LEDs with a total of about 50 to 70 W nominal electrical power.

You can also find photos in our photo gallery made with the same torches as the three videos above; for the UV torch see: #1, #2, #3, #4, and for the blue light torches see: #32, #33, #34, #35, #36, #37, #38, #39, #40, #41.

My equipment:

(Click on the images below for more details)

[Nikon P300 + Ikelite] My first camera is a Nikon Coolpix P300 with Ikelite underwater housing

[Olympus TG-1 + PT-053] My second camera is an Olympus Tough TG-1 (very similar to its successor TG-2) with Olympus PT-053 underwater housing

[HowToBuildYourOwnUltravioletDivingLamp#1] 1x Cree XT-E Royal Blue LED 450-455 nm 3-5W (depending on battery state of charge), based on LED Lenser D14 / LED Lenser Frogman (formerly 1x UV LED 395-410 nm 1W)

[HowToBuildYourOwnUltravioletDivingLamp#2] 2x Nichia NCSU033B 365 nm 6W, radiant flux (theoretically; 700 mA => factor 1.4) avg. 816 mW min. 756 mW max. 868 mW, based on Underwater Kinetics UK Sunlight C4 eLED (More info)

[Hartenberger maxi compact LCD] 21x3W blue LEDs 450 nm ~60W, Hartenberger maxi compact LCD     [NightSea Filters] NightSea filters

[HowToBuildYourOwnUltravioletDivingLamp#3] 4x Nichia NC4U133A 365 nm ~46W, radiant flux (theoretically; 0.625 A => factor 1.25) avg. 6.53 W min. 6.20 W max. 6.85 W, based on equipment from TillyTec (More info)

[HowToBuildYourOwnUltravioletDivingLamp#4] 1x Cree XT-E Royal Blue LED 450-455 nm 3W, based on ScubaPro Fuego LED Light

[HowToBuildYourOwnUltravioletDivingLamp#5] 3x Luminus SSR-90-B-R11-KG301 Blue 455-465nm 200lm @ 3.15A, based on equipment from TillyTec

[HowToBuildYourOwnUltravioletDivingLamp#6] 18x Cree XT-E Royal Blue LED 450-455 nm 5W, based on equipment from TillyTec

Commercially available equipment:

DISCLAIMER: is a joint project between me, the author of this page, and LM Engineering in the USA. is the author's own commercial web appearance.
It is my aim to maintain an attitude of rigorous neutrality on this page, and therefore, in the interest of fairness and openness, the reader is advised of the above-mentioned facts.
While I believe that and supply very high quality equipment, so too do the other vendors listed below, and no favoritism is intended or inferred. sells several fluorescence torches with blue high-power LEDs:
Blue Extreme $699 (12 LEDs)
Galaxy Blue $559 (6 LEDs)
FDG/RiFF TL Azur $475 $325 SALE! (10 LEDs)
FDG/RiFF TL 3000 BE $300 (3 LEDs) sells several fluorescence torches with blue high-power LEDs:
BlueFlameThrower €119
LED Lenser €89
Drop-in module for LED Lenser €25
Drop-in module + external filter €40

NightSea BlueStar Light $189.00 (1W)
NightSea BW-1 Blue/White Dive Light $575.00 (3W)
NightSea Filters for UK Light Cannon 100 HID $229.00 (10W; halogen-equivalent: 25W) ( ref1 ref2 ref3 ref4 ref5 )

NightSea+Light&Motion GoBe NightSea Light $200.00 (Backscatter $200.00)
NightSea+Light&Motion Sola NightSea Blue 1200 Video Light $550.00 (Backscatter $550.00)

NightSea official distributor (USA): Backscatter Underwater Video & Photo

NightSea distributor for Europe: Peter Patz, Mineralienladen Balingen, Tel/Fax +49 7433 2754 70/71, <mineralienladen AT aol DOT com> (More details)

NightSea alternative supplier (Germany): Paul Fischer's Webshop

NOT FOR DIVING: BlueLine NDT (Non-Destructive Testing)

Plongimage Fluo 330 phare special fluorescence 350.00 € (3x3W 60°)
Plongimage Phare video SOLARIS UV4200 + filtres 1'290.00 € (16x5W 120°)
Dyron UV Light Solaris 4200 920.00 € (16x5W 120° 440nm) (Review)
Bersub HD Pro 12 Fluo Wide 90 759.00 €

Hartenberger mini compact LCD (7x3.5W=28W, 21x2.5W=50W 450nm)
Hartenberger maxi compact LCD (7x3.5W=28W, 21x3W=60W 450nm)

mini compact LCD  (7.2V / 5.4Ah LiMn) 499.00 € + blue LED module  7x3.5W (spot or flood) 249.00 € = 748.00 € (28W)
mini compact LCD  (7.2V / 5.4Ah LiMn) 499.00 € + blue LED module 21x2.5W (spot or flood) 369.00 € = 868.00 € (50W)
maxi compact LCD (14.4V / 4.5Ah LiMn) 599.00 € + blue LED module  7x3.5W (spot or flood) 249.00 € = 848.00 € (28W)
maxi compact LCD (14.4V / 4.5Ah LiMn) 599.00 € + blue LED module   21x3W (spot or flood) 369.00 € = 968.00 € (60W)

Most of the commercially available lamps use blue LEDs instead of UV LEDs, with peak wavelengths around 450 nm (as opposed to my first couple constructions which use UV LEDs with a wavelength of 365 nm).
Tests have confirmed the prediction by Prof. Dr. Nico Michiels in a private communication that UV does indeed produce much less intense red fluorescence than blue excitation light.

Prof. Dr. Horst Grunz is sole distributor of the blue light version (English), which by the way includes a built-in dichroic filter, of TillyTec's Maxi uni dive light.
Prof. Dr. Grunz offers his expertise to everyone interested in underwater fluorescence. Contact him at
He also sells fluo diving equipment such as a flippable mask filter and several excitation filters (for strobes and white light torches) on his website.

Kowalski offers a fluorescence torch "mini-X-LED" with a single UV LED (80° flood, 3W, 395nm) for 159.00 €.

Glowdive (located in Bilbao, Spain) offers an ultraviolet underwater torch (of unspecified wavelength) for $369.00 / 260.00 € (including a filter screen on flexible mount), filters and other photographic equipment.
Reef Photo (located in Florida, USA) is a distributor for Glowdive equipment.
UnderWaterVisions (located in the UK) also sells Glowdive equipment.

Big Blue offers white light (LED) torches CF250 CF600 VL1300 VL1800 with Fluorodiving Kits (passive optical filters) which transform these white light torches into fluorescence torches.

Tektite offers a range of UV LED flashlights with either 365 nm or 375 nm and a varying number of LEDs: 2 (4.4mW/8.6mW, $39.95), 4 (8.8mW/17.2mW, $49.95), 7 (15.4mW/30.1mW, $95.95), 14 (30.8mW/60.1mW, $149.95), 40 (88mW/172mW, $398.00). They also have a number of CSI forensics lights.

HQRP-US sells a "HQRP 390 nm ultra violet waterproof diving LED flashlight + UV meter" on for $36.95 + $7.44 shipping.

The Swiss company Keldan (named after its founder Daniel Keller) sells several UW video lights for which a UV LED module (40 W, 5 W luminous flux, 400 nm) exists. Price is 1590 € or 1670 € for the torch (depending on the model) and 590 € for the UV LED module, i.e., 2180 € or 2260 € in total.

Diving Solutions Asia sells a single-LED blue fluorescence torch with mask filter for S$135. ( ref1 ref2 ref3 ref4 ref5 ref6 )

The Canadian company I-Torch sells the i-Torch Video Pro6 video and focus light for $649.00 with 4 white and 2 red (625 nm) LEDs as well as 2 violet LEDs of 420 nm for the observation of underwater fluorescence. The same company also sells the i-Torch Gen 1.3 Ultraviolet light for €498.75.

The Danish company WiseDive sells a 15 W (radiant flux?!?) UV dive torch with 395 nm wavelength and a maximum burn time of 4.5 h for €1'604.25, and a <60 W (= maximum power of the battery) blue light torch of 450 nm wavelength and a burn time of 2 h at 100% for € 1'489.25. Judging from the photo it seems that the latter torch is equipped with a dichroic filter, of undisclosed transmission characteristics.

Underwater Kinetics sells the SL4 eLED (L1) torch with a 395 nm UV LED for $119.99, and the Aqualite Video 90° torch with a 395 nm UV LED for $274.99.

Other useful resources:

The Sandwich Shoppe (LED drivers)
Deal Extreme (LED drivers)
LED Driver List (Independent)
LED Driver List (CREE)
LED Driver Tests
UV LED vendors:
Mouser (LEDs, electronic parts)
Farnell (LEDs, electronic parts)
Digikey (LEDs, electronic parts)
Future Electronics (LEDs, electronic parts)
Newark (LEDs, electronic parts)
cutter electronics (LEDs, electronic parts)
illumination supply (LEDs, electronic parts)
RapidLED (LEDs, electronic parts)
Nichia (LEDs)
S-Bend / Taiwan (LEDs) (Contact: Alan Hu <alan AT s DASH bend DOT com>), (LEDs, electronic parts) (LEDs) (LEDs) (electronic parts) (electronic parts)
Rosco (Permacolor Glass Dichroic Filters):
"Wood's Glass" #33650/#3650,
"Double Coated UV Pass" #33660/#3660,
"Primary Blue" #31080/#1080,
"Medium Red Blue" #34600/#4600,
"Primary Green" #35055/#5055,
"Turquoise" #34853/#4853,
"Sky Blue" #35590/#5590,
"Cyan" #35400/#5400,
"Mediterranean Blue" #31065/#1065.
Stagespot (Rosco Permacolor Glass Dichroic Filters)
B&H Photo (Rosco Permacolor Glass Dichroic Filters)
Lightco Nederland BV (Rosco Permacolor Glass Dichroic Filters) (Contact: Frank de Vos <frank DOT devos AT lightco DOT nl>)
Controllux B.V. (Rosco Permacolor Glass Dichroic Filters) (Contact: Lex Oudshoorn <lex AT controllux DOT nl>)
SUBSEA diving
CandlePowerForums (CPF)
Batteries and Chargers
18650 Batteries
(More info)
Michael Lux: Selbstbauprojekte für LED Lampen
Cable diameter vs. cross-sectional area, max. current, AWG table
M.D. Edmond Kay's Diving Medicine Home Page
Steffen Beyer's Dive Plan Calculator
(More links)

My experience:

August/September 2011:

In August/September 2011 I went to Hurghada/Egypt (Red Sea) and successfully tested [FluoDiving2011] [Diving2011] my second ultraviolet diving lamp: [UK_C4_eLED_1] [UK_C4_eLED_2]

Or see also on YouTube (or Picasa):

[ParrotFish] [ElFanadir1] [ElFanadir2] [ElFanadir3] [ElFanadir4] [ElFanadir5] [ElFanadir6] [ElFanadir7] [ElFanadir8] [ElFanadir9]

January 2012:

In January 2012 I went to the Dominican Republic (Caribbean Sea) and successfully tested [FluoRepDom2012] [RepDom2012] my latest (third) self-made UV diving lamp: [HowToBuildYourOwnUltravioletDivingLamp#3]

Or see also on YouTube or Picasa.

February 2012:

Participation in a marine research project [RSEC_Dahab] (fluorescence highlights coral damage, here in red) of the Red Sea Environmental Centre (RSEC) in Dahab, South Sinai, Egypt named Coral Project Dahab I with focus on coral diseases, damage, bleaching and diversity; using fluorescence to assess coral reef health (see also current list of projects).

(Show equipment)

More pictures:

[Dahab Daytime] Daytime pictures of me, courtesy of N. Milton and M. Laube, and by me
[RSEC_Team] Project album by N. Milton; needs Facebook account to view
[HorstGrunz] Project album by Prof. Dr. H. Grunz; needs Facebook account to view
[hotteatze] YouTube videos by Prof. Dr. H. Grunz

(Show entities)

May 2012:

On 4th of May 2012 I made a fluorescence night dive at Dreischor / Gemaal (see also or in Zeeland / The Netherlands with two buddies, and made this video [DreischorGemaal] using my Hartenberger torch and NightSea filters.

Or see also on YouTube or Picasa.

September 2012:

In September 2012 I returned to Dahab / South Sinai / Egypt [DahabSeptember2012] [DahabSeptember2012] mainly for testing [FireDiveGearTorches] fluorescence diving equipment.

June 2013:

On 7th of June 2013 I made a fluorescence night dive at Nieuwe Kerkweg / Den Osse in Zeeland / The Netherlands and made this video [NieuweKerkweg] using two of my [HowToBuildYourOwnUltravioletDivingLamp#5] torches with this [Nikon P300 + Ikelite] camera rig.

Or see also on YouTube or Picasa.

September 2013:

In September 2013 I went to Bonaire (Dutch Antilles/Caribbean) mainly to test new equipment, and in particular to investigate [Bonaire 2013] red fluorescence with green excitation light.

Or see also on YouTube or Picasa.

May 2015:

From 8th to 23rd May 2015 Prof. Grunz and the author held a Fluorescence Workshop at the Marsa Shagra Village of Red Sea Diving Safari:

[Marsa Shagra 2015]

Or see also on YouTube or Picasa and my English (24.4MB) or German (18.8MB) PowerPoint presentations.

Publications of ours:

The following are the unabbreviated original drafts which formed the basis for most of the above-mentioned publications
(but kept up to date as new information becomes available):

Experience by other people:



More spectacular footage: (BBC News Scotland) (BBC Two - Britain's Secret Seas)
Beyond The Blue Trailer (Vimeo)
Gallery Fluorescence
Fluorescent Corals
Fluorescent Shrimp
Fluorescent Lizardfish
And Then, There Was Fluo...
A Little Fluorescence
More Fluo
Fluo Science
Fluo Gobies
Fluorescent Shrimp
Beyond The Blue (7:37)
Beyond The Blue (2:45)
Fluorescent Shark (fluorescence in the deep sea) (fluorescence in the deep sea)
Fluorescent Goatfish changes fluorescent colours in just a few seconds
Doku: Im Farbrausch der Tiefe - Farbe als Sprache (1von3) (Water Colours part 2: A Colourful Language 1/3)
Doku: Im Farbrausch der Tiefe - Farbe als Sprache (2von3) (Water Colours part 2: A Colourful Language 2/3)
Doku: Im Farbrausch der Tiefe - Farbe als Sprache (3von3) (Water Colours part 2: A Colourful Language 3/3)

part 1
(episodes 1+2):
Fisheye Illusion
Trailer: Fisheye Fantasea
part 2
(episodes 3+4):
A Colourful Language
Trailer: Colour Talks
part 3
(episodes 5+6):
A Touch of Fluorescence
Trailer: Beyond The Blue
TV series Water Colours (3x50 min or 6x25 min) produced by Anita & Guy Chaumette / Liquid Motion Film for National Geographic
(The set of 3 DVDs costs 45 Euros plus shipping (from the UK) and can be ordered directly from
Trailer of a new series to come: The Significant Others
Trailer of a new movie to come: City Under The Sea


Télécharger le numéro #1 (PDF 31MB): "La nuit, les plongées sont psychédéliques" by Caroline Lepage
pages 55-58 of 62 (page numbers according to Adobe Reader), or pages 108-115 (page numbers at the bottom of each page)

In issue #57 (PDF 9.5MB) of Underwater Photography Magazine, there is an article "Ultraviolet photography" by Matej Simonic on pages 56-59.
(The latest issue of Underwater Photography Magazine is always free, back issues cost money)
See also more photos by the article's author and his videos Ultravijoli #1 (1:07) and Ultravijoli #2 (1:01) of Postojna Cave (10:00).

In issue #62 (PDF 9.2MB) of Underwater Photography Magazine, there is another article "Things that glow in the dark" by Alex Tyrrell on pages 43-47.

An article by Peter de Maagt about fluorescence diving named "Fluorescentie - Er Gloeiend Bij Zijn..." can be found on pages 66-70 in issue "Mei 2012" of the Dutch magazine "duiken".

Issues 03/2011 (PDF 13MB) and 04/2011 (PDF 13MB) of the German online magazine Dive Inside contain a continued article "Hightech-Fluoreszenz - Zauberwelt Korallenriff" by Prof. Dr. Horst Grunz.
This article is particularly interesting because it shows pictures of the innards of his DIY torches, which complement the images in his following document:

The most comprehensive document about underwater fluorescence with detailed illustrated explanations and many beautiful photos (including white light/UV light comparisons), by Prof. Dr. Horst Grunz, is the following:

Fluorescence (PDF 198MB) (English, Hi-Res)
Fluorescence (PDF 7.6MB) (English, Lo-Res)
Fluoreszenz (PDF 198MB) (German, Hi-Res)
Fluoreszenz (PDF 7.6MB) (German, Lo-Res)

In DiveInside (14.03.2013) there is another article "HiTec Fluoreszenz - Blau wird Weiß : Weiß wird Blau" by Prof. Dr. Horst Grunz.

In issue #55 (July 2013) of X-Ray Magazine there is an article "Fluoro Diving And Photography" (hires 47MB, midres 23MB, lores 14MB) on pages 84-91 by Kevin Deacon.

In the January 2014 issue of Dive Magazine there is an article named "Glow below" on pages 62-79 by Alex Tyrrell.

In issue #85 (PDF 18.8MB) of Underwater Photography Magazine, there is another article "Ikelite Fluorescence" by Phil Rudin on pages 44-46.

See also this media directory for some of these (and other) media.


Spiegel Online
Charles Mazel@NightSea
Adrian Baddeley/Charles Mazel/Jack Sullins/Jason Heller/Justin Marshall/Michael Aw/Stuart Westmorland
AlexanderMustard: Egypt, Red Sea. November 2010 [gallery] (buddy of Peter Rowlands)
AlexanderMustard: Fluorescence Photography. Cayman Islands. Feb 2011 [gallery]
AlexanderMustard: Fluorescence Photography, Devon, July 2011 [gallery]
PeterPatz@MineralienladenBalingen: Fluorescent Fossils
NikkiMcAllen ("First Fluorodive Guide in Thailand")
ScubaProAsia: Fluorodiving Photos and Movies
Fluorescence Photography (Neon)
BrandiEIrwin@UWPhotographyGuide: Capturing the glowing ocean: UV light and fluorescence
In pictures: Bio-fluorescent life in the Red Sea
biofluorescence shots
SciencePhotoLibrary: Underwater Fluorescence


John Rander - Photographing Coral Fluorescence UW
Blue Light Night Dive: Flourescent corals in Egypt (Surface Interval)
Corals' Fluorescent "Sunscreen" May Help Resist Bleaching (AMNH video interview with Dr. Anya Salih)
Red Sea Marine Life Becomes Neon Disco On Fluo-Dive (PICTURES) (
Night Divers Search for Organisms that Glow: Bioluminescense
Night diving by coral light
Why dull, brown corals light up like Christmas when you shine blue light on them (
The red, green, blue and yellow sea: Fluorescent lights turn the bottom of the Red Sea into a sponge disco (
A Last Dive for Glowing Animals (NYTimes)
The Naked Coral Hypothesis (NYTimes)
In Pristine Reefs, a Vast Library of Species (NYTimes)
Glowing Wildly on a Moonless Night (NYTimes)
Night Diving in Search of an Eerie Glow (NYTimes)
The Holy Grail of Fluorescent Proteins (NYTimes)
Biofluorescence Under Blue Lights (NYTimes)
Night dives like you've never experienced before (Roatan, Honduras)
Red at depth: Colors disappear underwater, but not always
Love and War: The Essence of Luminosity (NatGeoNewsWatch)
Blue Light Night Dive: Fluorescent corals in Egypt
The Fascinating Phenomenon of Coral Fluorescence
Learn about Fluorescent Corals and How to Take Video of Them
GestaltSwitchExpeditions: "Fluorescence" in marine organisms Le blog de la fluorescence sous marine / The underwater fluorescence web site
Fluorodiving: Science and Beauty of Coral Fluorescence
Fluoro Dive - What is a Fluorescence Night Dive
2020VISION: Glow in the dark
Under the lights: The gorgeous world of glow diving
Hochschule Esslingen - Fluoreszenz von Korallen

Websites: (scientific background, standard and custom-made gear for fluorescence diving) (scientific background of and gear for fluorescence diving) (German underwater fluorescence portal and webshop by Paul Fischer) (homepage of Prof. Dr. Horst A. Grunz)


Dive4Photos Underwater Photography Workshop - Koh Tao, Surat Thani, Thailand
A Hidden World of Intense Color: New Developments in Underwater Fluorescence Imaging and Science (Talk Announcement: The Boston Sea Rovers Show March 9th+10th 2013)
The Lux* Maldives Underwater Festival (01-Mar-2012)
Sign up for the Underwater Festival (04-Mar-2012)
LUX* Island Resorts announces the first edition of the lux* maldives underwater festival (04-Apr-2012)

Forum threads:

Ultraviolet Night Diving "Thinking of doing this in Bonaire. Anyone have a chance to try this? Could you share your experience? Sounds amazing with the flourescence being quite different from bioluminescence. Jeremy"
"Fat Star" Octa 8x SST-90 Colossus Led Flashlight @ 18.000 lumens -more beamshots- "Hello, instead of doing something serious with my money like going to Ibiza, I put some parts together, in the beginning there was this lathe and a piece of aluminium: [...] "Fat Star" Octa 8x SST-90 in 4" Colossus Turbo Head: [...]"
Sammelthread zum Thema UV-Lampen "So, da es ja immer wieder Kaufberatungsthreads für UV-Lampen gibt (vor allem fürs Geocachen) werde ich hier mal alle Links sammeln, welche ich bis jetzt zum Thema gefunden habe. Wenn ihr noch was interessantes gefunden habt postet das bitte hier oder sagt mir Bescheid. Es wäre sinnvoll, wenn sich die Diskussionen hier der Übersichtlichkeit halber auf ein Minimum beschränken würden. Es soll ein reiner Informationsthread sein. Bitte schreibt auch eine kurze Beschreibung zu den jeweiligen Links."
Fluo-diving on the cheap? "After Britain's Secret Seas showed fluorescent stuff (technical term) in St Abbs, I have been wondering how I can see the same. Last night I was poking about a bit on the internet and found people selling blue torches/filters and orange filter visors for considerable money, so I thought I should ask if anyone knows how I can do this on the cheap? Many thanks in advance, Nick K."
DIY LED and UV dive lights, Converting lights to bright or ultraviolet LEDs "I am about to order some parts to try my hand at DIY LED lights, but before I do, I thought I'd post to learn from others. I want to build cheap high-powered LED dive lights for both the normal light spectrum as well as specifically to excite fluorescence underwater. "Cheap" here means recycling some obsolete dive lights I own, with incandescent / halogen bulbs but useable shells. It occurs to me that the original Princeton Tec 400 is a good candidate for this conversion because it is made for a medium size reflector (about 52mm), has a mechanical switch that can be modified to work, and has the capacity for two 18650 lithium-ion batteries, which gives the possibilities for 3.7 or 7.4v (parallel or series)."
Magic fluorescence in night dives with HiTecLEDs "Hi all divers, I just returned from Diving in ElQuseir, Egypt. There I tested a HiTec Fluorescence lamp in Night-Dives. I have constructed the lamp with parts of Sandwhich Shoppe McR-20 reflectors and stepdown converters (Shark Buck 3A). The emitters are 4 blue OSRAM SMT modules (4 LEDs per module each). A description can be found on the PR-Page of OSRAM under Success Stories OSTAR LED in HiTec fluorescence lamps highlight the beauty of red sea corals. On my home page you will find an explanation what the technique is good for and also a 12 minutes movie (stream). For Fun-dives the technique it is a new underwater world. It is the magical transformation of drab-colored to brightly glowing color-saturated specimens that makes fluorescence so magical. The diver gets the impression that he (she) dives in underwater flower garden. This is indeed the case since my lamp illuminates larger areas in contrast to commercial available lamps with one LED only (16 in our lamp, 16fold brighter). Also on YouTube you will find the movie about this technique. From 6 hours night dive I have selected the highlights in this 10 minute version."
Nichia 365nm Light offerings "Hi guys, Through the years I have received numerous requests for a flashlight hosting one of the Nichia High Power UV LED's. I've done a few customs but pretty much just built some for myself and a few others. I finally bit the bullet and had a run of custom MCPCB's made for the latest generation UV LED, 033A." (bookmark)
Source for nichia NCSU033B uv led? "Hi, I don't know if this is the right cat, but i am searching for a nichia NCSU033B uv led. Does anybody know a source for a single NCSU033B ? Thanks, markus"
UV dive lights "In a random conversation with a dive buddy, I started wondering if anything underwater would fluoresce. Then we started talking about how to build an ultraviolet dive light. Turns out to be pretty easy."
Dive Blacklight (UV Light)? "Has anybody seen an underwater blacklight (ultraviolet light) for sale? I know many corals and things are fluorescent so I was wondering if a uv light would make them glow with strange colors -especially on a night dive. Any ideas?"
UV Night Dive?? "I've seen a few posts about UV night dives but have yet to see any details. Are they offered through dive shops? Is it something that you do on your own. It looks like a VERY cool dive. Any info you guys have is greatly appreciated."
DIY UV dive light "Hey, folks. I've been working on building my own dive light specifically designed as an exciter for the green fluorescent protein present in many underwater critters. [...] I've attached a picture of the light and the one salvageable picture I took using it, of a fluorescing anemone (the green of the anemone is its fluorescence, the purple is from the light). It was hard to get good pictures as 1) it only is visible when there's no white light around, whether it's coming from the sun or another diver's light, and 2) I didn't have the UV light mounted on the camera housing like I should have. The end result was a set of pictures that were either too dark or really blurry from being shaken around by the Cozumel currents."
Biofluorescent fun with your HID light "Night Diving just took on a whole new look with just a $30.00 dichroic Wood's Glass (Black Light) dichroic filter and your favorite HID light"
Biofluorescent video and GC East End trip report "June 5 - 12th - The four of us got off the plane and immediately did one of my best all time dives at Eden rock - lots of bottom time, schools of jacks circling us, swim throughs, Fairy Basslets all around (love those colors!) etc etc - ALL for price of a tank rental. Stayed at The Reef resort and dove with Ocean Frontiers - wayyy professional, wayy courteous, set up and cleaned gear for you, way accomodating to our changing schedule - top notch."
Biofluorescent (glowing coral) videos from night dive #2 "Finally uploaded the videos to YouTube of the glowing corals from my 24 Watt HID with the dichroic black light filters. Search SB on "Biofluorescence" to get more info on the light. What you actually see underwater is way cooler than the videos show, as the dark violet light is very dark until you hit something that fluoresces and then its like someone turned on a light switch inside the corals. I even found a bristleworm that glowed orange."
UltraViolet light... "Does anyone have any experience with an underwater UV light? Especially in making one from UV LED's. I've made some regular LED lights with white light and red LED's but some folks have talked about using UV to make the colors pop with corals, etc. But would UV damage coral??"
Night dives with an ultraviolet lamp ("blacklight") - taking advantage of bio-fluorescence "I read about using an ultraviolet lamp during night dives in the following book: [...] Such an ultraviolet ("black light") lamp is supposed to give a spectacular view underwater by way of bio-fluorescence. In the meantime I found a suitable (standard white) LED diving lamp and a suitable UV LED and was able to modify the lamp accordingly (see also the pictures annexed hereto). Maybe this will inspire you to do the same."
WTB/Feeler: Nichia 365nm LEDs "I am having a hard time sourcing any of the Nichia 365nm LEDs, be it the "smaller" 325mw or the newer 950mw version. -->Nichia Those are really strong, emit almost no visible light at all, and are far more powerful and efficient than other manufacturers models. Does anyone want to sell one of these? Any shop known which sells the LEDs only? If all these fail: Groupbuy? They have their price though, 100$ is the minimum to expect for the smaller version."
Feeler: Nichia high power 365nm LEDs "HERE I was trying to buy some of the new NICHIA high power 365nm LEDs. I am of course talking about the 250mw, 325mw and 950mw output versions. Yes, thats the actual optical output, not the electrical input as with those other "1 watt LEDs". What did I find out so far? there are three versions of those monster-LEDs: NCSU033A is around for years already, 250mw output. NCSU033B is new, like an update, and 325mw. NC4U133 has four dies inside, still in the same small size, with 950mw output!"

Articles related to fluorescence diving:


Wissenschaft aktuell: Übersehen - Viele Korallenfische erzeugen rotes Licht
Bild der Wissenschaft: Meister des Verschwindens
Spiegel Online: Riffbewohner leuchten im Dunkeln
Prodivers: Bezaubernd, skurril & phänomenal...
RedSea-EC: Fluoreszenz im Riff - Glühende Korallen
Dive Inside: Wissensurlaub am Roten Meer - Meeresbiologisches Seminar "Fluoreszenz"
Ägypten: Naturschutz im Neoprenanzug (Fluoreszenz-Tauchgang)

English: The Light Beyond
BlueZooAquatics: Charles Mazel on Coral Fluorescence
BlueZooAquatics: Coral Fluorescence in the Marine Aquarium
UliBeyer: Fluorescent Lures for Fishing

Scientific articles and books related to fluorescence diving:


Red fluorescence in reef fish: A novel signalling mechanism? (PDF 6.6MB) (video supplement #1, video supplement #2)
The inherent visible light signature of an intense underwater ultraviolet light source due to combined Raman and fluorescence effects (PDF 226KB)
Spectral measurements of fluorescence emission in Caribbean cnidarians (PDF 643KB)
Reference List (CharlesMazel@NightSea)
Effects of cold stress and heat stress on coral fluorescence in reef-building corals
Green fluorescent protein regulation in the coral Acropora yongei during photoacclimation (full)
Cold induces acute stress but heat is ultimately more deleterious for the reef-building coral Acropora yongei (full)
Aglow in the Dark: The Revolutionary Science of Biofluorescence

Operators who offer fluorescence night dives:

(Sorted geographically according to country from West to East, otherwise unsorted)

Hawaii, USA (Pacific Ocean): Big Island Divers (Review)
Grand Cayman (Cayman Islands): Ocean Frontiers (Review) (first in Cayman Islands)
Key Largo, Florida (Caribbean): Keys Diver (Alternative)
Bonaire (Dutch Antilles): VIP Diving / Blue Divers
Bonaire (Dutch Antilles): Buddy Dive Resort (Review)
Bonaire (Dutch Antilles): Great Adventures Bonaire / Harbour Village Beach Club Bonaire (Source)
Bonaire (Dutch Antilles): Divi Flamingo Beach Resort (unconfirmed) (Source)
Bonaire (Dutch Antilles): Dive Friends Bonaire (Source)
Bonaire (Dutch Antilles): Flow (Source)
Bonaire (Dutch Antilles): Bonaire Dive and Adventure (Source)
Grenada (Caribbean): Aquanauts Grenada
Spain (Mediterranean Sea): Euro-Divers Cala Joncols (Roses/Costa Brava)
Egypt (Red Sea): RSEC Red Sea Environmental Centre (Dahab)
Egypt (Red Sea): Sinai Divers (Sharm-El-Sheikh, Dahab)
Egypt (Red Sea): Extra Divers (Dahab)
Egypt (Red Sea): INMO Divers (Dahab)
Egypt (Red Sea): Sea Dancer Dive Center (Dahab)
Egypt (Red Sea): Reef 2000 (Dahab)
Egypt (Red Sea): Black Rock Dive Centre (Dahab)
Maldives (Indian Ocean): Prodivers (first in the Maldives)
Maldives (Indian Ocean): Euro-Divers Maldives (Review)
Maldives (Indian Ocean): Diving Centers Werner Lau (Filitheyo, North Nilande Atoll)
Thailand (Koh Tao): UV Dive Koh Tao (Review; see bottom, 1st June 2011) (first in Thailand)
Thailand (Koh Tao): (fluo-photography training with Alex Tyrrell)
Thailand (Koh Tao): Glow Scuba
Indonesia (Sulawesi): Wakatobi Dive Resort (first in Indonesia)
Indonesia (Gili Trawangan): South Sea Nomads (Review)
Philippines (Dumaguete/Puerto Galera): Atlantis Dive Resorts and Liveaboards (first in the Philippines, introduced by Alex Tyrrell)
Philippines (Puerto Galera): Blue Ribbon Dive Resort
Philippines (Moalboal/Cebu): Magic Island Dive Resort
Philippines (Panglao): PrAna Divers (Alternative)
Australia (Cairns/QLD): Deep Sea Divers Den (Rev1, Rev2) (first in Australia)

Fluo-Diving's Who is Who:

Dr. Charles Harris Mazel <mazel AT psicorp DOT com>, <nightsea AT nightsea DOT com> (pioneer, scientist, manufacturer)
Dr. Anya Salih <a DOT salih AT uws DOT edu DOT au> (scientist)
Prof. Dr. Horst Artur Grunz <horst DOT grunz AT uni-due DOT de> (scientist)
Prof. Dr. Nico K. Michiels <nico DOT michiels AT uni-tuebingen DOT de> (scientist)
Dr. David F. Gruber <David DOT Gruber AT baruch DOT cuny DOT edu> (scientist)
Dr. Vincent Allen Pieribone <vap5 AT email DOT med DOT yale DOT edu> (scientist)
Dr. Melissa S. Roth <melissasroth AT gmail DOT com> (scientist)
Dr. Dimitri D. Deheyn <ddeheyn AT ucsd DOT edu> (scientist)
Guy & Anita Chaumette <production AT liquidmotionfilm DOT com> (photographers and filmmakers, ex-managers of Wakatobi Dive Resort)
(More people)


[Steffen Beyer]

Steffen Beyer

Suggestions, additions and corrections are welcome!

People, organisations and products are listed on this page in arbitrary order, which does not imply any judgement of importance or quality, or any other hidden meaning.

I do not pursue any financial profit with this web page (which is one of the reasons why it is free of ads and cookies), it is intended to be purely informational and helpful to experts and enthusiasts of fluorescence diving.

One of the aims of this web page is that I would like to seed the formation of a community of fluorescence diving experts and enthusiasts, for the exchange of ideas, experiences, hints, photos, videos, discoveries, and other useful or interesting information.

As Dr. Charles H. Mazel has put it: "The odds of you going in the water and finding something, seeing some animal fluorescing, that no-one else in the entire history of the universe has ever seen is probably over ninety percent! Anywhere in the world. Simply because so few people have done this." (Quoted from Liquid Motion Film/National Geographic Water Colours series)

Therefore I believe that even scientists doing research in underwater fluorescence would benefit from the combined experiences and discoveries of such a community. The scientists can only be so many, and more eyes see more.

Long-term idea: A half-scientific, half-practical international conference on underwater fluorescence with scientific as well as practical and artistic contributions from researchers and practitioners, also with photo exhibitions and video shows.

For instance I would be very interested to know how John Blazy came to invent his new material, Dichrolam, which is essentially a dichroic filter (e.g. used to turn a HID dive light into an ultraviolet lamp for fluorescence diving) laminated with a UV-cured polymer, if I understood correctly.


I can not possibly check the integrity and genuineness of all the sites and businesses linked to on this page.
Therefore use these links and businesses with caution and at your own risk!

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