You have to check out this gallery of amazing underwater walrus photography by Goran Ehlme via the BBC:
http://news.bbc.co.uk/2/shared/spl/hi/pop_ups/07/sci_nat_beasts_of_the_deep/html/1.stm
Here’s the link. This is amazing stuff. I’m going to do some research on Goran’s work, and I’ll post a followup.