I don't know the story behind this video, but it does seem like we're looking at a future Darwin Award winner.
Posted by Rick MacPherson over at Malaria, bedbugs, sea lice and sunsets, it shows several divers practicing to be shark whisperers with one or more great white sharks. I've done a lot of diving and I've NEVER seen anything like this.
Riding the dorsal fin of a huge shark? Again and again? Patting it on the snout? I don't think this needs a "don't try this at home" warning.
I'll ask Rick where this came from.