I bought some of those wireless video cameras from x10 that you see advertised all over the net. These tiny cameras take decent video and transmit it by 2.4 GHz radio to a receiver up to 100 feet away. I modified both the camera and the receiver to work off of batteries, and plugged the video signal that came out of the receiver into the "video in" jack on my camcorder so i could go anywhere and record the video signal that the portable camera sent.

For this exercise, Stan and Kim and I sealed the camera in a watertight box and floated it in a hotel pool. We discovered that water highly attenuates the signal, but as long as the box stayed within a couple inches of the surface we could get a useable signal. They make a version of the camera with a 60' cord and better low-light sensitivity. Maybe I'll try putting one of them in the box and going a little deeper.

On a different occasion, we also flew the camera on a tiny balsa-wood frame supported by 28 helium balloons.