The submarine's luck changed for the better on her sixth foray, when she sank the Miranda about 30 nautical miles (56 km; 35 mi) northwest of Peterhead in Scotland on 20 January 1940.

U-57 was one of six U-boats that took part in Operation Nordmark; carrying out reconnaissance in the area of the Orkney and Shetland Islands for a subsequently unsuccessful sortie by the German capital ships Scharnhorst, Gneisenau and Admiral Hipper between 18 and 20 February 1940.

Patrol number nine saw the boat sweeping the area of the North Sea off the English/Scottish borders, Orkney and Shetland and all points east, with no result.

U-57 had moved to Bergen in Norway; HMS Tetrarch (N77), a British submarine, fired three torpedoes at the U-boat in the entrance to Kors fjord on 15 July 1940: they missed.

She also successfully attacked the Manipur 8 nautical miles (15 km; 9.2 mi) northwest of Cape Wrath, (on the northern Scottish mainland).

Her next victim was the Atos which went to the bottom in three minutes about 30 nautical miles (56 km; 35 mi) north of Malin Head (in Ireland)[4] on 3 August.

She damaged the Havildar 25 nautical miles (46 km; 29 mi) northeast of Malin Head on 24 August 1940 and sank the Cumberland but was unsuccessfully attacked by British warships the next day.

Returning to Germany, she was relegated to duties as a training boat and sank after a collision with the Norwegian ship Rona at Brunsbüttel (northwest of Hamburg) on 3 September 1940 with the loss of six of her 25 crew members.