UB-81 struck a mine on the night of 2 December 1917 in the English Channel to the southeast of the Isle of Wight off Dunnose Head. The crew of 34, commanded by Oberleutnant zur See Reinhold Saltzwedel, managed to raise the forward torpedo tubes above the surface and seven crewmen escaped before a collision occurred with a British patrol boat and she sank; another source claims that 35 men were aboard and that six survived.
UB-81 had an incident on December 2, 1917, when it struck a mine in the English Channel. The crew of 34, under Oberleutnant zur See Reinhold Saltzwedel's command, managed to escape before the submarine came into contact with a British warship and sank.