Don Walsh (November 2, 1931 – November 12, 2023) was an American oceanographer, U.S. Navy officer and marine policy specialist. While aboard the bathyscaphe Trieste, he and Jacques Piccard made a record maximum descent in the Challenger Deep on January 23, 1960, to 35,813 feet (10,916 m). Later and more accurate measurements have measured it at 35,798 feet (10,911 m).

Walsh was born in Berkeley, California on November 2, 1931. He graduated with a bachelor's degree in engineering from the U.S. Naval Academy in 1954, and later, a Master's degree in political science from San Diego State University, and a PhD in physical oceanography from Texas A&M University.

Walsh served 24 years in the U.S. Navy upon graduation from the Academy, spanning the Korean and Vietnam Wars. He served as a submarine officer and was a qualified Navy Diver.

He attained the rank of captain by the time he retired. He spent fifteen years at sea, mostly in submarines, and was a submarine commander. He also worked with ocean-related research and development for the Navy.

Walsh was appointed as special assistant to the Assistant Secretary of the Navy for Research and Development from 1971 to 1972.

Serving as Dean of Marine Programs and Professor of Ocean Engineering at the University of Southern California, Walsh initiated and directed the university's Institute for Marine and Coastal Studies. In 1989, his company, International Maritime Incorporated, contracted a joint venture with the P.P. Shirshov Institute of Oceanology to establish an underwater maintenance company, Soyuz Marine Service, which continues to operate in the Russian Federation. Walsh continued to support ocean sciences in his work on the Ocean Sciences Board at the National Academy of Sciences.

He managed a marine consulting business beginning in 1976, and as of 2010^[update] conducted about five deep-sea expeditions per year.

Walsh held a faculty appointment at Oregon State University in the College of Earth, Ocean, and Atmospheric Sciences.