The Ehime Maru and USS Greeneville collision was a ship collision between the United States Navy submarine USS Greeneville and the Japanese fishery high school training ship Ehime Maru on 9 February 2001. The collision happened about 9 nautical miles off the south coast of Oahu, Hawaii, United States. In a demonstration for some civilian visitors, USS Greeneville performed an emergency surfacing maneuver. As the submarine surfaced, it struck Ehime Maru, a fishery high school training ship from Ehime Prefecture, Japan. Within minutes of the collision, Ehime Maru sank. Nine of its crewmembers were killed, including four high school students.
Many Japanese, including government officials, were concerned over news that civilians were present in USS Greeneville's control room at the time of the accident. Some expressed anger because of a perception that the submarine did not try to assist Ehime Maru's survivors. The submarine's captain, Commander Scott Waddle, did not apologize immediately afterwards. The Navy conducted a public court of inquiry, placed blame on Waddle and other members of USS Greeneville's crew, and dealt non-judicial punishment or administrative disciplinary action to the captain and some crew members.
In response to requests from the families of Ehime Maru's victims and the government of Japan, the USN raised Ehime Maru from the ocean floor in October 2001 and moved it to shallow water near Oahu. Once there, Navy and Japanese divers located and retrieved the remains of eight of the nine victims from the wreck. Ehime Maru was then moved back out to sea and scuttled in deep water. The Navy compensated the government of Ehime Prefecture, Ehime Maru's survivors, and victims' family members for the accident. Waddle traveled to Japan in December 2002 to apologize to the ship's survivors and victims' families.
The accident renewed calls by many in Japan for the United States to make more effort to reduce or eliminate crimes and accidents involving U.S. military personnel who injure or kill Japanese citizens. In response to the accident, the Navy changed its policies regarding civilian visits to its ships.