Aron Ralston was an experienced climber who became trapped by a boulder while climbing alone in Blue John Canyon, Utah in 2003. For nearly 5 days with his right arm pinned by the boulder, he endured dehydration, hunger and the possibility of death before resorting to amputating his arm with a pocket knife in order to survive. He was later rescued and went on to write a memoir about his ordeal, becoming a motivational speaker advocating the importance of letting others know your plans when embarking on risky activities alone.