Here is a picture of a beautiful arch located in Tennessee. We came across it while mountain biking, and thought that it might be fun to leap off as it was probably around a 50 foot drop from the top ledge. Both my brother and I had our scuba gear with us, so we explored the area prior to jumping, to make sure there were no underwater trees or other obstacles. After we knew it was safe and the water was deep enough, the rest, they say, is history. Here is a picture of four of us on various ledges.
Have water, will travel...
This is a pretty cool view from behind on one of the jumps.
Even though this may look a little crazy, it was a lot of fun. If you are thinking of doing something along these lines, make sure to check the water first for proper depth and to make sure there are no trees or any other obstructions under the water.
I have actually done quite a bit of diving into the water from high places - now up to around 80 feet, and offer a warning to not keep your arms outstretched (like you see in the above pictures) while hitting the water when you are jumping from over 20 feet. It will definitely sting, could bruise your arms. and depending on the height, could even break them. It's also better to hit water that the surface is being broken (say by a waterfall) rather than calm and flat water like this photo. Other than that, plug your nose if you need to, and enjoy the rush!