The Ehime Maru and USS Greeneville collision was a ship collision between the United States Navy (USN) Los Angeles-class submarine USS Greeneville (SSN-772) and the Japanese fishery high school training ship Ehime Maru (えひめ丸) on 9 February 2001, about 9 nautical miles (17 km) off the south coast of Oahu, Hawaii, United States. In a demonstration for some civilian visitors, Greeneville performed an emergency ballast blow surfacing maneuver. As the submarine surfaced, she struck Ehime Maru, a fishery high school training ship from Ehime Prefecture, Japan. Within 10 minutes of the collision, Ehime Maru sank.