Hmm, I’ve swum near dolphins, though not actually alongside them (about 20 yards away). I don’t guess that really counts, though.
I haven’t really done anything on the list, although there are a few there that I would definitely include on my personal list. Here are the things from the list that I’d like to see/do, in order of probability (from highest to lowest):
Exploring the Pyramids: I hope to be doing this at some point in the near future–I definitely plan to visit Egypt. In addition to the Great Pyramids, I’d also like to see the Temple of Hatshepsut, the Stepped Pyramid of Zoser, the temple complexes at Karnak and Luxor…
Walking the Inca Trail: Like with Egypt, I’d like to combine this with other ancient sites–the Nazca line drawings, Lake Titicaca, Tiahuanaco, etc.
See Aurora Borealis: A natural phenomenon that I’d love to see.
Driving down Route 66: The mother of all road trips. Low on the probability list, since I doubt I’d try it until I get a lot of vacaction time or retire.
Walking the Great Wall of China: This would be cool, though I have no idea if I’ll ever make it to China.
Something that is not on the BBC list, but which is up high on my “to-do” list:
Visit India: For a long time, I’ve been fascinated with India and Indian culture. I would love to see the thousands of historical and artistic sities (the Elephanta Caves, the Khajuraho temples, the Ajanta caves, countless Buddhist stupas and Hindu temples, Taj Mahal, etc.), and the Ganges, and all the colors of daily life. I’m not sure when I would go to India, but it’s one of my “must-sees” during my lifetime.
The BBC list does include Travelling on the Orient Express as one of the top 50 items, so maybe I could combine that with my own passage to India.