Acrylic is the traditional material choice for subsea glazing, but if you think FEA is going to substitute for experience, you are in, er, over your head.
You need to _go_to_ Sea World and talk to the people who designed and built the few parts that actually are underwater. Visit some commercial submarine builders, and some people who have done serious fabrications in acrylic.
OR, better, rent some engineers with specific experience to help you with the study. No, I don't know any, but somebody here probably does.
Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA