Here are a few web sites that you might find useful if you are looking for more in-depth information about the physics of scuba diving and other related topics.
In addition to the sites we've listed below, you might also find it beneficial to search Google for "scuba diving physics".
There are many sites out there with good information about scuba diving, and Google is a great tool for uncovering those sites.
Saudidiving.com - Diving Physics
How Stuff Works - How SCUBA Works
Flash.net - Buoyancy
The Laws and Physics of Scuba Diving - Powerpoint
Diving Physics - Quick Equation List
The Gas Laws and SCUBA Diving