water rafting is a sport I have only seen in New Zealand. To
go blackwater rafting you need a wet suit because the water is bloody
cold. Then you need a cave with an underground stream. It
helps if the cave has glow worms. Glow worms help sell the
tourists on the idea of going underground and hanging out in a grungy
slimy old wet suit in freezing cold water :-)
you get into the underground stream, you float along said stream on an
inner tube. The highlights for many is jumping backwards off water
falls into the pools below. As bad as I make it sound,
it really is quite a thrill and anyone visiting New Zealand should give
it a try.
here for a slide show.
Here is a
website where you can learn more about the sport.