major submarine basin of the central part of the north Pacific Ocean, between the Line Islands to the east and the Marshall Islands to the west. It occupies a large area of the north Pacific and extends westward to a zone of trenches, the Andesite Line (a region of intense volcanic and seismic activity), which includes the Aleutian Trench, the Kuril Trench, the Japan Trench, and the Yap Trench. The deepest section of the Central Pacific Basin lies more than 21,300 feet (6,500 m) below sea level. The basin is bordered by the submarine Mid-Pacific Mountains on the north, and the Phoenix Islands and the Tokelau Islands mark its southern reaches south of the Equator. Its floor is covered with the remains of oceanic organisms that once inhabited its waters. The comparatively warm Pacific North Equatorial Current and the Pacific Equatorial Current flow westward and eastward, respectively, in the basin.