I have been following the project of the Underwater Realm in the UK for some time now on vimeo: http://vimeo.com/realmpictues. They are making a series of underwater films with the R3D Epic and plan to show them at the Cannes Film Festival this next year. In doing their project they found the need for studio type lighting in their UW scenes so the made their own lights. And for the application, I must say, genius. The link below is a two part video of the system they created.
Currently they are in need of funding and have turned to Kickstarter.com to solicit funds. http://www.kickstarter.com/projects/realmp...nderwater-realm
I have no affiliation with this project, but thought some people would really be interested. If you donate $50, you can get the DIY plans for their light system, which they say cost about $1500 to build two banks of lights and a battery pack that can last for almost 8 hours. Obviously there are restrictions to be connected to the battery pack, but like I said, for a specific application, it looks really good.
As always with UW video, light is the main issue. I could see these types of lights being used to light up a reef in controlled conditions or lakes or quarries (as they used them).
Again, I have no affiliation with this project, but I may donate to get the light plans.