David Louis Mearns, O.A.M., M.Sc., (born 10 August 1958), is an American-born United Kingdom based marine scientist and Oceanographer, who specializes in deep water search and recovery operations, and the discovery of the location of historic ship wrecks.
Mearns was raised in Weehawken, New Jersey, where he attended Weehawken High School, graduating in 1976. He subsequently graduated B.Sc. in Marine Biology from Fairleigh Dickinson University in 1980, and obtained a Masters degree in Marine Geology from the University of South Florida in 1986.
From 1986 to 1995 Mearns was employed in the commercial undersea surveying industry in a managerial capacity. In 1990 he worked on the criminal investigation into the foundering of the freighter Lucona, and in 1994 located the wreck of the ore-bulk-oil carrier MV Derbyshire. Relocating to England in the mid 1990s, he established Blue Water Recoveries, Limited, a commercial company that locates and researches historic deep-sea shipwrecks across the globe.
In 2001, to coincide with the 60th anniversary of the Battle of the Denmark Strait high seas confrontation between the naval forces of the British Empire and Nazi Germany during World War II, Mearns successfully led an expedition funded by Channel 4 Television to locate and film on the seabed of the North Atlantic Ocean the wrecks of the Royal Navy flagship H.M.S Hood, and its nemesis, K.M.S. Bismarck. An extended television documentary entitled The Hunt for the Hood was produced from the expedition.