Simpson was killed on 9 May 2013, during training for the 34th America's Cup, when the Swedish Artemis Racing team yacht he was aboard capsized near Treasure Island in San Francisco Bay. The yacht, a 72-foot catamaran with a rigid, wing-like sail, was turning downwind (bearing away) when it flipped over and broke into pieces. Simpson was trapped underneath its hulls for approximately ten minutes, and attempts to revive him by doctors afloat and subsequently ashore were unsuccessful. The cause of the accident is unknown. An investigation was initiated by the United States Coast Guard which involved San Francisco police and the America's Cup management.