From The Lenz media shows us that there are more cool things to do with waterfalls than trying to go down them in a barrel.
Sean Lenz and Kristoffer Abildgaard of the San Francisco-based multi-media team dropped a variety of high-powered Cyalume glow sticks into various waterfalls in Northern California and proceeded to take long exposure shots varying from 30 seconds to 7 minutes. Thus capturing a beautiful glow trail of color lights submerged through the current.
Hopefully they retrieved the light sticks after the shoot.
You can see the pics in higher resolution on From The Lenz.