The feature was discovered by members of the USAS in flights from the ship "Bear" in February 1940, and was further delineated from air photos taken by US Navy Operation Highjump in December 1946. The sound was first noted to parallel the entire south coast of Thurston Island, thereby establishing insularity, by the USN Bellingshausen Sea Expedition in February 1960. Named after the sloop of war "Peacock" in which Captain William L. Hudson, in company with the tender "Flying Fish" under Lt. William M. Walker, both of the USEE, 1838–42, sailed along the edge of the pack ice to the north of Thurston Island for several days in March 1839.