Mapping the Mariana Trench

US scientists have mapped the deepest part of the world's oceans in greater detail than ever before.

The Mariana Trench in the western Pacific runs for about 2,500km and extends down to 10,994m.

This measurement for the deepest point - known as Challenger Deep - is arguably the most precise yet.

The survey, conducted by the University of New Hampshire's Center for Coastal and Ocean Mapping (CCOM), was completed to help determine the exact extent of US waters in the region.

Jim Gardner from the CCOM explained the process and findings to BBC science correspondent Jonathan Amos.