I have been using the Xacti from Sanyo for many years. I use it above and under water (not too deep though, no good for scuba!).Takes good stills and video, quality good enough for viewing on screen or ipad. Not good enough for projection in presentations.
I am reluctant to take a non-waterproof camera in the boat as I have lost some expensive gear due to soaking, including a camera that was in a pelican case which apparently warped in heat so that the seal failed.
Prior to the Xacti I had an older Olympus digital 2 Mega Pixel camera with a 10x optical zoom (great feature), which I waterproofed with a special underwater housing made for that camera. A bit clonky but it worked above and under water.
Keep seals clean and free of sand!