In 2010, the UK Department for Transport awarded Odyssey Marine Exploration an exclusive salvage contract for the cargo from the SS "Gairsoppa", a steel-hulled British cargo steamship that was enlisted in the service of the United Kingdom Ministry of War Transport and sunk by a German U-boat on February 16, 1941, approximately 300 miles southwest of Galway, Ireland. Odyssey announced it discovered the shipwreck site in 2011 at a depth of 4700 meters with the recovery of 61 tons of silver. Through a two year expedition, they recovered over 110 tons of silver ingots. The expedition was the subject of a three part Discovery Channel docuseries called "Silver Rush". In addition to silver, 717 letters, the largest collection of mail found on any shipwreck worldwide, was recovered and archaeologically conserved from the shipwreck and are now on display at the Postal Museum in the UK.