There have been five ships of the Royal Navy to bear the name HMS Urchin after the Sea urchin:
HMS Urchin was a U-class destroyer of the British Royal Navy that saw service during the Second World War.
Urchin formed part of the British Pacific Fleet during the latter part of the War.
Following service in the Second World War Urchin was held in reserve at Harwich, then Chatham Dockyard until 1952. Between 1952 and 1954 she was converted into a Type 15 fast anti-submarine frigate, by Barclay Curle, Glasgow. Following this she was allocated the new pennant number F196. She re-commissioned on the 3 June 1954 into the 3rd Training Squadron, based at Londonderry.
In 1956 she went back into reserve at Portsmouth Dockyard. In 1957 she was refitted as a training frigate and re-commissioned for service with the Dartmouth Training Squadron. She subsequently served off Iceland during the 'Cod wars' in 1959.
Urchin was decommissioned in 1964 and placed on the Disposal List. Before sale for breaking-up her stern structure was removed and fitted in sister ship Ulster during 1966. The hulk was later towed to Troon where she arrived in August 1967 for demolition.
ORP Sokół (Polish: Falcon) was a U-class submarine (formerly HMS Urchin) built by Vickers-Armstrong at Barrow-in-Furness. Shortly after launching in September 1940 she was to be commissioned by the Royal Navy as HMS Urchin, but instead was leased to the Polish Navy due to a lack of experienced submarine crews. A sister boat to Dzik, both boats operated in the Mediterranean from Malta, where they became known as the "Terrible Twins".
Shortly after her trials, the boat was handed to her Polish crew, in accordance with the Polish-British Military Alliance and amendments of 18 November 1939 and 3 December 1940. On 19 January 1941 the Polish banner was raised and the boat, commanded by Commander Borys Karnicki, was moved to Portsmouth. There she spent half a year patrolling the Bay of Biscay off the French port of Brest. In September she was moved to Malta, where she was attached to the 10th Submarine Flotilla. She took part in the naval runs on the Italian ports of Taranto and Naples. She also escorted numerous convoys in the Mediterranean. On 28 October of that year, Sokół achieved her first victory by heavily damaging the Italian auxiliary cruiser Città di Palermo. On 2 November in the Gulf of Naples she sank the 2,469-ton transport ship Balilla, with her sister HMS Utmost. On 19 November of the same year, she forced the anti-submarine nets and entered the port of Navarino, where she damaged the Italian destroyer Aviere. She was attacked by Italian torpedo boats and destroyers, but all of the depth charges missed and Sokół managed to escape from the harbour, sinking an additional transport steamer (5,600 tons) with three torpedoes. On 12 February 1942 she boarded and then sank the Italian wooden merchant schooner Giuseppina (362 tons) in the Gulf of Gabes.