U.S. Naval Radio Station Otter Cliffs was a United States Navy radio receiver facility located in Acadia National Park on Mount Desert Island, south of Bar Harbor, Maine. The station was commissioned on August 28, 1917, under the command of Lt. Alessandro Fabbri, who had personally cleared the land, built and equipped the station, and offered it to the government in exchange for a commission in the Naval Reserve and assignment as Officer-in-Charge. Prior to the war, Fabbri was a licensed radio amateur with the U.S. Government issued call sign 1AJ.