Interesting stuff here. I live at 4,800 feet and the nearest dive site (non pool) is the Crater. A warm water spring in a mountain - depth 64 feet. To get to the crater I drive over a pass around 8,000. then drop down to the crater at about 5,500 feet (elevations are near guesses, Scott, if you see this chime in). After a couple dives we repeat the process in reverse. This seems to be incredibly dangerous given the discussion here yet it is what many scuba divers here do on a regular basis. Makes a super short 1,000 flight seem something superfulous but obviously there is something here I'm missing. It will be interesting to follow this thread.