HMNB Devonport (HM Dockyard, Devonport)

His Majesty's Naval Base Devonport is one of three operating bases of the Royal Navy in the United Kingdom, situated on the Hamoaze, the estuarial reach of the River Tamar, at Devonport in the west of Plymouth, Devon, England. Owned by the Ministry of Defence under Navy Command and operated by the Royal Navy, it is under the Naval Base Commander, Devonport, a post held since 2022 by a Royal Marine officer. It is the sole nuclear repair and refuelling facility of the Royal Navy and the largest naval base in Western Europe.

The base homeports the fleet's Type 23 frigates, becoming their sole base port in December 2025, and is designated the base port for the Type 26 frigates on delivery. Also based there are the survey vessels HMS Scott and HMS Magpie, the ice patrol ship HMS Protector, and Sea-class survey and diving craft. It formerly hosted the Devonport Flotilla, since merged into the Surface Flotilla, and ceased to base attack submarines with the retirement of HMS Triumph in early 2025. Resident commands and units include Fleet Operational Standards and Training, the Hydrographic, Meteorological and Oceanographic Training Group, HQ Amphibious Task Group, the Southern Diving Group, Defence Estates South West and the Ministry of Defence Police. Morice Yard has been the headquarters of Surface Fleet Command since 2022. RM Tamar, opened in 2013 beside the Weston Mill Lake berths, houses 47 Commando (Raiding Group) Royal Marines with its assault and landing craft training squadrons, and is the Royal Navy's Amphibious Centre of Excellence. HMS Vivid, the Plymouth Royal Naval Reserve unit, is in the South Yard.

The base covers 650 acres with four miles of waterfront, five basins, tidal berths and dry docks, and includes the Fleet Accommodation Centre (HMS Drake) for personnel. Ship repair and maintenance is carried out by Babcock International as Devonport Royal Dockyard, privatised in 1987 and co-located with the base; Babcock owns about a third of the site. Facilities include the covered Frigate Refit Complex in the former Keyham dry docks, the Submarine Refit Complex at No. 5 Basin with docks for nuclear submarines, and the Quadrangle workshops. Out-of-service nuclear submarines are laid up at the base pending disposal.

Established from 1691 on the Hamoaze as a Royal Navy dockyard designed by Edmund Dummer, the yard expanded northwards through the Keyham Steam Yard of 1864 and the Keyham Extension completed in 1907. Shipbuilding ended with HMS Scylla in 1968. Nuclear submarine refitting began with the opening of the Submarine Refit Complex in 1981, and Devonport became the Royal Navy's only nuclear refitting base in 2002.