The SS Gairsoppa was a British steam merchant ship which was torpedoed by a German submarine while making its way to Galway, Ireland in 1941. The ship and its 7,720 tonnes of cargo, including silver bullion, iron, and tea, lay undisturbed for decades until it was found in 2011.
Some 2,800 bars of silver worth around $52 million (£41m) in today's money have since been salvaged, along with teapots, silk, and – most miraculously – letters from British soldiers in India, which had survived in an air pocket.