I'll add the "swimming with dolphins" experience. I'm sure that this one varies depending on where you do it and who you're with. I did this years ago in the FL Keys and was told beforehand (and have since read in several reviews of the experience) that it would be life-changing, that you would develop a deep spiritual connection with the dolphins, etc.
Frankly, it was disgusting. A bunch of dolphins--which I generally find to be beautiful creatures--swimming around in an enclosed area, defacating constantly on and around you while the trainer repeatedly warns everyone that the dolphins can trap you underwater if they become "amorous." Not my cup of tea.