Do you like to dive or snorkel? I'll bet you have used those disposable 35mm underwater cameras, haven't you? They are good for taking photos up close and in shallow water but not good for deepwater. What you really need to create and save those underwater memories is an underwater digital camera.
Underwater digital cameras are used by divers all over the world and not just for personal use. Those who make their living from the ocean like marine photographers, biologists, and scientists use underwater digital cameras to film and study marine life. The photographers sell their videos and make a good living from it, the scientists use them to study and learn more about the creatures they are interested in. You are more than likely in none of those categories, probably like me, you are just a lover of the water. I thoroughly enjoy being able to bring back evidence of what I have seen underwater with a camera.