end of April and, on 2 May, the ship sailed Suva for Singapore, where she arrived on 22 May for a ten-week refit. HMS Hydra then sailed for the Indian Ocean and was surveying the waters around the Seychelles from September to November. She then had a maintenance period in Mombasa, returning to survey off Mahé. Christmas 1975 was spent in Port Victoria and the ship sailed the Seychelles on 29 December for the Persian Gulf. The main survey was on the traffic separation routes about from the eastern end of the Persian Gulf, around the Tunb Islands off Iran. The surveys began with a visit to Bandar Abbas and Iranian naval personnel were attached to the ship for the duration. The ship remained in the area until the end of April, working mostly out of Bandar Abbas, but visits were paid to Karachi (for maintenance), Masirah and Dubai. Passage through the Suez Canal into the Mediterranean was followed by a two-week maintenance period in Malta in late May 1976. Surveys then began in the western Mediterranean, until the middle of September, with visits to Palermo, Malta and Gibraltar. She sailed the Rock on 14 September for Portsmouth, her first sighting of the UK in five years. She then underwent a refit at Vosper Thornycroft in Southampton, when her living accommodation was extensively modernised; boat surveys of Portsmouth harbour, and other south coast harbours, were carried out during the refit. No chart of Chichester harbour had previously existed, and parts of the Poole area had not been surveyed since 1878. HMS Hydra completed refit in August 1977 and was operational again on 26 September. She sailed 24 October for Iran, calling briefly at Gibraltar and Malta. She arrived at Bandar Abbas, in company with , on 23 November and surveys then began along the Iranian coast in the Gulf of Oman. Christmas 1977 was spent in Bahrain. She was employed on surveys in the Persian Gulf, off Iran, for much of 1978 and 1979. On 1 January 1979, as one of four Royal Navy survey ships forming the Persian Gulf Surveying Squadron (, and ), HMS Hydra was at anchor in Char Bahar bay on the south-east coast of Iran. Later in the month, the ship was at Bombay for maintenance, resuming surveys off Iran on 4 February. The surveys were almost complete when the ship was ordered to Bandar