This video came out last year, but it's making the rounds again and is totally worth it.
Three divers off the coast of Canada's Vancouver Island discover a Giant Pacific Octopus that has camouflaged itself in the rocks and plants. They can grow to be 16 feet across and weigh over 100 pounds.
Anyway, one of the divers goes in for a closer look, so the octopus starts checking her out too. It extends its legs to touch her arms and then her shoulders and then starts to engulf her head like she's prey.
When they engulf their prey to feed, they inject them with paralyzing saliva and then dismember them with their beaks. The real danger to the diver would have been if it had messed with her breathing equipment. One of the other divers eventually comes over and untangles them.