Ocean basins are composed of the seafloor and all of its geological features (such as islands, trenches, mid-ocean ridges, and rift valleys) and vary in size, shape, and features due to the movement of Earth’s crust (lithosphere). Earth’s highest peaks, deepest valleys, and flattest plains are all in the ocean.

Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawai?i, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.