The fall happened during a parachute-jump training exercise out of Hurlburt Field, Fla., according to Air Force Times.
U.S. Coast Guard personnel were assisting the Air Force as a search for the airman got underway in water about a mile and a half south of Santa Rosa Island, Fla., along the Florida Panhandle, WKRG-TV of Mobile, Ala., reported.
The Florida Fish and Wildlife Conservation Commission was also assisting in the operation, the station reported.
The Coast Guard said the airman, identified only as a staff sergeant, dropped about 1,500 feet into the water and his parachute deployed, WEAR-TV of Pensacola, Fla., reported.
Crew members aboard the C-130 initially saw the airman treading water but lost sight of him while making a turn in an effort to pick him up, the report said.
Responding crews were adjusting their search area based on currents in the area, Coast Guard Petty Officer Kamil Zdankowski told the Northwest Florida Daily News.