Here's one I've been looking forward to, in spirit since witnessing the breathtaking footage of Planet Earth, and in practice since first stepping foot in Africa - cage diving with the Great White Sharks.
Before describing the experience there's a need to address the inevitable and already existing concerns about diving with the great white. In particular, some environmentalists take issue with the activity because they allege that diving with these predators conditions them to view human beings as food. After a day of close quarters observation, both in the cage and from the ship's deck, I can tell you with full confidence that this concern is both unwarranted and unfounded.
To begin with, conditioning an animal to change its natural response patterns takes time, and a unique aspect about the South African great whites is that they are a completely open population, meaning that any given individual shark is only spending about three or four weeks in the area. That's far to little time to ingrain a new conditioning pattern. More to the point, whomever asserts this as a concern has a feeble understanding of conditioning. In order for sharks to be conditioned to view human beings as food, they need to receive some form of reward that causes them to believe this. For starters, they aren't managing to eat human beings during these trips. More importantly, they aren't permitted to eat anything else either. The bait used to attract sharks is pulled away before they can reach it. The entire strategy of shark diving focuses on piquing the shark's natural curiosity in order to bring it within sighting distance. They are not fed, and most importantly human beings are never presented as food, nor are they interested in them as such. Case closed there.
As far as the experience itself goes, its a phenomenal opportunity to appreciate one of natures most specialized creations. In the cage itself we witnessed great whites of up to 4 metres in length passing within a foot of our eyes. The largest of the species can top 6 metres, but there was no shortage of awe and appreciation for the beauty and power of these animals as it was.
In totaly, we witnessed four individual great whites in close quarters, and on one occasion saw one consume a giant lion's mane jellyfish measuring a full metre in diameter. The shark sucked it back with one motion, and even the marine biologist on board the vessel enthused that she had never so much as read about a great white preying on jelly fish, let alone witness it. The sighting will be her next academic submission to the professional journals.
More than anything the trip was an opportunity to witness a species deeply in peril. Despite their dense numbers on the southern tip of Africa, sharks across the world are in steep decline. Each year 100,000,000 (no that is not a typo) die at the hands of long line fishing nets and cast aside as by catch (but only after their fins are lopped off as delicacies, often with the sharks still alive). Meanwhile, collectors across the globe are willing to pay upwards of $100,000 for their very own set of great white's jaws for display as a trophy to god knows what.
The work of the tour leaders and conservationists who bring these creatures to the public eye is one of the biggest forces working in favour of their protection, and from start to finish, I have nothing but praise for the professionalism of this trip and the enormous respect they help spread for the great whites of South Africa.