Tamu Massif is an extinct submarine shield volcano located in the northwestern Pacific Ocean. The possibility of its nature as a single volcano was announced on 5 September 2013, which, if corroborated, would make Tamu Massif the largest known volcano on Earth. It is located in the Shatsky Rise about 1,600 km (990 mi) east of Japan. Its summit lies about 1,980 m (6,500 ft) below the surface of the ocean, and its base extends to a depth of about 6.4 km (4.0 mi). The volcano is about 4,460 metres (14,620 ft) tall.