German submarine U-778

German submarine U-778 was a German Type VIIC U-boat built in World War II. She only completed one combat patrol and sank no Allied ships. She was surrendered to the Allies at Bergen on the 8 May 1945.

On 4 December 1945, she was being towed offshore, to be scuttled as part of Operation Deadlight, but foundered and sank before reaching the scuttling ground, at a point 55.53333°N, -7.11667°W, 16 mi North East of Malin Head in around 70 m of water. The wreck was rediscovered by marine archaeologist Innes McCartney in 2001.

In 2007, Derry City Council announced plans to raise the boat to be the main exhibit of a new maritime museum. Many of the other Operation Deadlight U-boats were used for target practice and sunk by gunfire, torpedoes, rockets or bombs. U-778, by contrast, is remarkably intact and lies in relatively shallow water.

On 3 October 2007, an Irish diver, Michael Hanrahan, died whilst filming the wreck as part of the salvage project. In November 2009, a spokesman from the council's heritage museum service announced the salvage project had been cancelled for cost reasons.