The U-550 was cruising off the east coast of the United States back on April 16, 1944, when it torpedoed the gasoline tanker SS Pan Pennsylvania. The Pennsylvania was headed to the UK with 140,000 barrels of gasoline, along with a protective convoy of three ships - the USS Joyce, USS Gandy and USS Peterson.
Although the U-boat attempted to evade detection by concealing itself under the sinking freighter, sailors on the USS Joyce managed to identify the German vessel and damage it by dropping depth charges.
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According to Mazraani, the U-550 is one of several World War II-era German U-boats to be discovered off the US coast. The next step, he says, is to try and contact the sailors or the families who were manning the escort vessels, as well as the crew of the tanker and German U-boat.
WWII German U-boat found off Massachusetts coast