My longest canopy ride was about 12,000 ft. I had a premature bag deployment on a tandem skydive. As soon as I set the drouge, the canopy opened. I had about a 15 minute parachute ride. My student passed out on me twice but was fine for landing. Talk about some fun!
I've also done a few hop and pop jumps from 12,500 when trying out a new canopy. Last one I did, I beat the tandems down.
Joe