You might want to check this out. It's one of the options that came up when I Googled "waterproof voice recorder" Looks like it may work for you.
"Far better it is to dare mighty things than to take rank with those poor timid spirits who know neither victory nor defeat." - Theodore Roosevelt

-USMC Corporal Hess Sherrod B:6/6/84 D:4/6/09 I miss you, my brother.