I have one - it's based on Vue 5, but will work just as well in Vue 6.

http://users.tns.net/~mwalter1/caustics.pdf

Then, take a look over at GeekatPlay.  Lots of tutorials and one on underwater.  

http://geekatplay.com/index.php  See tutorial #30

P.S.  My tutorials will not be available on my site for much longer - I will be moving them to ShareCG (they host for free and are quick for downloads).  

Peggy

LVS - Where Learning is Fun!  
http://www.lvsonline.com/index.html