(CNN) A group of underwater treasure hunters has salvaged hundreds of bottles of rare cognac and liqueur from a ship that was sunk by a German U-boat during World War I.

Divers and unmanned underwater vehicles from Ocean X Team and iXplorer worked around the clock for a week last month to haul up case after case of booze from the Swedish steamer SS Kyros, which has been sitting in about 250 feet of water (77 meters) in the Baltic Sea.

They recovered 600 bottles of De Haartman & Co. cognac and 300 bottles of Benedictine liqueur -- a brand now owned by Bacardi, Peter Lindberg with the Ocean X Team told CNN.

"We don't know yet if it is drinkable. We get a fraction of smell from the Benedictine bottles and it smells sweet and from herbs," Lindberg told CNN. "We can't get any sense of smell from the cognac bottles, but that might just be in order since it should not smell through a cork."

He said they are researching the cognac and talking with Bacardi to try to determine the value of the haul.