Hi as it so happens I have talked about this on a different thread just recently, but enough blabbing by me here are some pros and cons.
PRO: Awesome learning experience. Make cool submersible bot. And water bots are just plain cool.
CON: Lots of work (might not be able to do in 6 weeks). $Expensive$. Hard design( MUST BE WATER PROOF!).
Hows that for starters?