Over the last 15 years, the sport of Canyoneering has really caught on. I have done a little canyoneering, but usually I spend my leisure time on the sides of mountains (rock climbing). Canyoneering is a great sport, with lots of adventure ... combining exploring, climbing, rappelling, and adventure swimming.
However, the new sport is claiming lives. At first blush - it wouldn't seem that hiking down a canyon could really be all that complicated. But serious canyon exploring involves a myriad of dangers.
This first link gives various info about Canyons, but if you want to enjoy some "close encounter" stories ... go down to the Section titled "Recent Accounts". It is eye-opening - what can go wrong in these remote canyons.
See RECENT ACCOUNTS to get an idea of the dangers ...
http://www.bogley.com/forum/showthread.php?24485-Canyoneering-LinksThe second story got a lot of attention from the press, when 7 canyon explorers were killed in a flash flood. What the media did NOT explain ... is that some of these people were experienced, and they were watching the weather very closely. But they still drowned in Keyhole Canyon - due to unexpected flash floods from a nearby thunderstorm.
The news link shows a group photo of the canyon explorers before their outing - really a tragic reminder about the terrible loss - when you are in the wrong place at the wrong time.
http://www.cbsnews.com/news/searchers-find-final-missing-person-in-zion-national-park/Pete