First time I came across a submerged computer it was at
http://www.pugetsystems.com/submerged.php.
Tey even has done some testing, and a short build log. Follow the link for some numbers. It's not impressive, but imensely cool to look at. I've dabbled with the thought of doing a project like this, but have put it on hold indefinately. Also there are other homebrew systems around if you search youtube
