Aron Ralston severed his own forearm with a knife in Bluejohn Canyon in Southeastern Utah, after getting trapped while canyoneering.
During a solo slot canyon descent on April 26, 2003, he dislodged a boulder which trapped his right wrist against the canyon wall. After five days, he freed himself by amputating his arm at the mid forearm and managed to hike out of the canyon to seek help.
The incident was chronicled in the autobiographical book Between a Rock and a Hard Place and the movie 127 Hours.
