EMS spokesman Stuart Brideaux says the man in his late teens appears to have gotten out of the vehicle after the crash near the Ghost Lake Reservoir Campground northwest of Calgary early Sunday.
Two other men, believed to be in their 20s, who were also in the vehicle were pronounced dead when rescuers rappelled towards the bottom of a riverbed to reach them.
The survivor endured intense cold, and Brideaux says it may have taken him several hours to get to the road.
He was airlifted to a Calgary hospital with frostbite, hypothermia and other injuries.
Police are still investigating the cause of the crash.
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