Have a look at the Pentax Optio w30, Waterproof to 5ft deep, stills + movies both with sound. Its dust proof as well. Up to 7meg and two timers 2 or 10 second for selftake.
I use the w20 my self and the w30 is the next step up. Add to the fact that its only the size of a packet of fags, look it up its worth it !. Check out the trusted reviews site, even the R.N.L.I. use them on board.