I have had both.... I like the Olympus 720 SW because it is waterproof to 10ft, and also shock proof, to 5ft, I have tested this...
Both cameras are very good though for the sport of kayak fishing... I literally abused both cameras with saltwater, they have been soaking in my footwell, and they held up good... I just try to wash them off with fresh water... Although I dropped my Pentax, and it broke... They make a new Olympus that goes to 30ft.... I don't like the cameras with dive housing, if you get water on the lens, then it comes out blurry... I like to be careless.... It is also cumbersome, my Olympus fits in my lifevest pocket...
chris