Thanks for coming to our humble board to check this out. Yeah, I can attest that IR underwater isn't done much but there are others who have indeed tried it. I got my inspiration from Imran Ahmed (Singapore) a Nikon Pro photographer who did a few IR shots. He used a housed D70. I decided after seeing those to convert an additional D7000 body to experiment with IR underwater. The difficulties in Underwater IR (in the traditional sense of IR photography) are simply that water absorbs ALL IR light VERY quickly. I may not know the physics or the science as well as some esteemed forum members here but Infrared photography as we know it works that way. You can modify the filters of course to limit the spectrum of visible light that comes in and also UW... "proper" IR using 720nm filters brings you close to the IR spectrum which happens to be the first shades of colors to be absorbed in the water.followed by red. For the shot below, I was in 1 ft of water with both strobes fired at FULL blast on a sunny day. it didn't get very far.
IMHO, I think IR is a little wasted on the gorgeous colors the underwater world has to offer. To the untrained eye of the non-diver, most will tell you that they would prefer to see the colors. Unlike topside photography, many simply do not know what the REAL colors are underwater and as such are not as wowed when compared to bluish hair, perfect skin, white leaves and surreal winter like scenes... these are simply lost when it comes to viewing seascapes. Imagine me showing you a false color or IR shot of an alien planet.... see what I mean? False colors brings a completely different problem to the table... many creatures such as crinoids and soft coral already come in multiple colors! having it changed does little for the viewer! The trained diver's eye may spot the difference but many may not notice with just a passing glance.
There is however a place for IR photography underwater if used creatively and if limits are understood. IR brings out different textures, contrasts, etc. You begin to see things in a different light! (Forgive the pun). Forget colors. If you shoot a hard shelled crab, ALL the spots and stripes you see on it's shell will disappear. The calcium on the shell reflects IR light incredibly well.... you will get a plain white featureless crab! The beautifully speckled shrimps may do the same! On almost transparent anemone cleaner shrimps, even IR will pass through the shells. In the "Pokemon" Nudibranch from the original post, the subject was a pale opaque white color with orange stripes and black tips on the rhinopores. Under IR, it looks almost translucent! The speckled appearance is not visible under normal light. Here, you can even see the stomach tract! I believe this was from the algae this creature ingests as part of it's diet!
If IR photography as how we know it is to be done underwater, it's thus mostly left to the realm of macro shots. IR that has become fully absorbed means jet black backgrounds anything over 15cm away, even with the most powerful strobes. That is not to say close focus wide angle shots are not possible.... The photo below was taken with a Tokina fisheye lens and a 1.4TC. The fish was almost touching the dome port of my housing. It took a lot of patience to creep up to him to get this. Taken in just 3m of water in VERY bright sunlight. I would have been happy to wear a pair of sunglasses under my mask then. This is where you can see the effect of IR in water.... light may come in but infrared is the FIRST in the color spectrum to get killed off and absorbed...way earlier than the color red.
It's not hard from this to figure out what the creative possibilities are for IR in underwater shots. jet black backgrounds, higher contrasts... think like topside IR and monochrome photography. The shot below was made using the same fisheye and TC combo but with the addition of a handheld snooted strobe with the light fired at full blast downwards.
I don't really know of any shots or reviews that might have been done about underwater IR.... you can check my flickr page and my FB though. I will probably be updating with more shots in Nov and Dec after my trips to Brunei, Sipadan, Anilao and Lembeh
You can look me up on FB as Kay Burn Lim