HMS Hydra was a reciprocating engine-powered Algerine-class minesweeper built for the Royal Navy during the Second World War. She was badly damaged during the war and was scrapped in 1947.

Convoy JW 55B was an Arctic convoy sent from Great Britain by the Western Allies to aid the Soviet Union during World War II. It sailed in late December 1943, reaching the Soviet northern ports at the end of the month. All ships arrived safely.