This is extremely rare colour footage of the battle-cruiser HMS Hood and its crew at sea in 1939. Two years later, the ship and some of the men in this footage were at the bottom of the Denmark Strait after a fateful encounter with Hitler's flagship, Bismarck. Eighty years ago today, the mighty Hood was sunk with the loss of 1,415 lives - just three men survived - as she and brand-new battleship HMS Prince of Wales attempted to stop the Bismarck and cruiser Prinz Eugen raiding Britain's supply l

The "last salvo" of HMS Hood was likely a final, unintentional firing from its forward guns caused by the magazine explosion as the ship was sinking, rather than a deliberate act of defiance. Evidence from eyewitness accounts and inquiries suggests the explosion triggered a chain reaction that fired the 15-inch guns already loaded. While this has been interpreted as a final defiant act, the more plausible explanation is that the ship's destruction caused the guns to fire as it went down. Eyewitn

NATO has released footage of a submarine sinking a frigate during a training exercise. | Sky News Australia

Sinking Ship Simulator: The Royal Navy's Damage Repair Instructional Unit - How do you train sailors to save a sinking ship? Sure, you can teach them the theory, but there's no replacement for having to hammer softwood wedges into deck and bulkhead splits that are spraying cold, high-pressure water in your face. | Tom Scott