While Aron Ralston was on a canyoneering trip in Blue John Canyon, a boulder dislodged, crushing his right forearm and pinning it against the canyon wall. Ralston had not told anyone of his hiking plans and knew no one would be searching for him. Assuming that he would die, he spent five days slowly sipping his small amount of remaining water while trying to extricate his arm. He eventually ran out of water and began to drink his own urine. After five days of trying to lift and break the boulder, Ralston prepared to cut off his already-dead arm by levering it against a chockstone, which snapped the radius and ulna bones. Using the dull blade on his multiuse tool, he cut the soft tissue around the break. He then used the tool's pliers to tear at the tougher tendons. After freeing himself, he had to rappel down a 65-foot (20 m) sheer wall, then hike out of the canyon. While hiking out, he encountered a family on vacation who alerted the authorities. He was ultimately rescued by a helicopter search team.