The sunken shipwreck of a British cargo ship from World War II could hold up to $200 million worth of silver. Publicly traded treasure hunting company Odyssey Marine Exploration is on a salvaging mission to extract the metal from the ship.

The S.S. Gairsoppa was sunk by a Nazi submarine in 1941. It was part of a convoy traveling from India to Liverpool when it was intercepted and struck by the U-boat after it broke away from the group to refuel in Galway, Ireland. A single torpedo was enough to breach the hull and finish the ship, according to The New York Times. When the ship sank, 84 of 85 crewmen drowned, the lone survivor lasting 13 days in a lifeboat.

Odyssey won a bid from the English government to recover the ship's cargo, which includes 218 metric tons of silver. Under terms of the agreement, Odyssey will be allowed to keep 80 percent of whatever it can pull from 15,400 feet below the ocean to the surface.

We were fortunate to find the shipwreck sitting upright, with the holds open and easily accessible. This should enable us to unload cargo through the hatches as would happen with a floating ship alongside a cargo terminal, stated Odyssey CEO Greg Stemm.

The news shot Odyssey's shares up 40 percent to $3.73 in premarket trading on Monday.

The silver on the S.S. Gairsoppa was going to be used to fund the war effort in Great Britain. All of the bullion was privately owned and insured by the British government. The boat was sunk by decorated Kriegsmarine officer Ernst Mengersen, who sunk 12 ships on 11 patrols for Nazi Germany.

Being the son of a merchant mariner who worked for the same shipping line as the Gairsoppa's and as a former merchant mariner myself, the visit to the site via [remotely operated underwater vehicle] was particularly personal, stated Neil Cunningham Dobson, Odyssey's Principal Marine Archaeologist.

Even though records indicate that the lifeboats were launched before the ship sank, sadly most of her crew did not survive the long journey to shore. By finding this shipwreck, and telling the story of its loss, we pay tribute to the brave merchant sailors who lost their lives, added Dobson.