Modern professional and semiprofessional cameras can generally withstand moderate exposure to the elements and an occasional bump or knock, but dunking them in 30 feet of water is an entirely different proposition. For that sort of use, you'll want to look into rugged compact cameras, and this excellent video review compares three of the best models.
Coming to you from DP Review, this great review takes a look at the Ricoh WG-6, the Olympus TG-6, and the Panasonic TS7. While cameraphones can take great pictures and video in a lot of situations nowadays (and even outshine these cameras in some scenarios), they're not made to handle physically demanding scenarios, and they're certainly not made to handle being shot with underwater. You could buy an underwater housing, but those typically cost well over a thousand dollars, and if you're not dedicating yourself to that genre, they can be an unjustifiable expense. That's where a rugged compact comes into play. They're designed to withstand the elements, shoot underwater, and handle impacts with ease. They also make great pocket cameras if you want something you can take anywhere and never worry about. Check out the video above to see which model is right for you.