Blackwater
Blackwater diving off Kailua-Kona, HI is an interesting experience. Essentially attached to a line 40' under the boat, in 6000' of water watching the biggest migration of animal life in the world as all the small animals come up from the deep at night. It also takes some skill with the right camera hardware as these animals are between .5 cm and 2", and moving against a very dark background.