RNAS Portland (ICAO: EGDP) was an air station of the Royal Navy, situated at the Isle of Portland, Dorset, England. It was established in 1917 on the western edge of Portland Harbour as HMS Sarepta. From 1959 the station shared the name HMS Osprey, the anti-submarine establishment based at Portland, with helicopters used for research and development in anti-submarine techniques. RNAS Portland remained operational until 1999.