HMS Ambush (P418), was an Amphion-class submarine of the Royal Navy, built by Vickers Armstrong and launched 24 September 1945. In 1948 she took part in trials of the Schnorkel. In 1951 she heard and decoded a distress message from HMS Affray, which was sunk with the ultimate loss of all 75 hands. In 1953 she took part in the Fleet Review to celebrate the Coronation of Queen Elizabeth II.