National Geographic photographer Paul Nicklen was in Antarctica to capture shots of leopard seals. One approached him, jaws wide and ready for biting...and if you haven't heard the rest of the story yet, you need to watch this brief clip.
I'm not man enough to dive into freezing waters to document the lives of animals that could rip off my head without a second thought, but I'm sure glad that YouTube exists so I can sit here in my underwear and enjoy the experience vicariously.
I saw some leopard seals while kayaking in Antarctica and would not want to get in the water with them. This is as close as I got: