HMS Hydra

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{{Use British English|date=January 2017}}

Seven ships of the Royal Navy have borne the name HMS Hydra, after the Lernaean Hydra of Greek mythology:

• {{HMS|Hydra|1778}} was a 24-gun sixth rate launched in 1778 and sold in 1783.
• {{HMS|Hydra|1797}} was a 38-gun fifth rate launched in 1797. She was used as a troopship from 1812 and was sold in 1820.
• {{HMS|Hydra|1838}} was a wooden steam {{sclass|Hydra|sloop|0}} paddle sloop launched in 1838, used as a survey vessel after 1852, paid off in 1868 and sold in 1870.
• {{HMS|Hydra|1871}} was a {{sclass|Cyclops|monitor|0}} turret ship launched in 1871 and sold in 1903.
• {{HMS|Hydra|1912}} was an {{sclass|Acheron|destroyer}} launched in 1912 and sold in 1921.
• {{HMS|Hydra|J275}} was an {{sclass|Algerine|minesweeper}} launched in 1942. She was damaged by a mine in 1944 and not repaired. She was scrapped in 1945.
• {{HMS|Hydra|A144}} was an oceanographic survey vessel launched in 1965, sold to Indonesia in 1986 and renamed Dewa Kembar.