In 2006 I fulfilled one of my dreams, diving with whale sharks. I had tried in Australia but it was cancelled due to bad weather. When I visited the Philippines I went to Donsol, where there was a very interesting project developing to increase interaction between local people, tourists and whale sharks.
You go with local people in small wooden boats, and when you see a shark, they take you closer and you jump out of the boat with your flippers and diving goggles near the shark. Despite being vegetarian it's pretty impressive in size, up to 20 meters, and has an enormous mouth, up to 2 meters