This site from the U.S. Geological Survey allows you to access detailed images of the continental margin around the United States. There is additional information about the sonar methods used, and a wealth of additional sources listed.

A short description of the world's deepest ocean trench. Includes diagram and map.

Ocean explorer Robert Ballard takes us on a mindbending trip to hidden worlds underwater, where he and other researchers are finding unexpected life, resources, and even new mountains. He makes a case for serious exploration and mapping....