She had a dive time of 48 seconds and was capable of operating at a depth of 50 metres (160 ft).

When submerged, she could operate for 52 nautical miles (96 km; 60 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 8,660 to 9,450 nautical miles (16,040 to 17,500 km; 9,970 to 10,870 mi) at 7 knots (13 km/h; 8.1 mph).

UC-56 was fitted with six 100 centimetres (39 in) mine tubes, eighteen UC 200 mines, three 50 centimetres (20 in) torpedo tubes (one on the stern and two on the bow), seven torpedoes, and one 8.8 cm (3.5 in) Uk L/30 deck gun.

On 24 May 1918, the U-boat arrived at Santander, Spain after a dangerous three-day voyage in a severely damaged condition.

The crew of UC-56 were interned, the Germans reported to the Spanish authorities that their submarine had been seriously damaged by Christabel, and that they had had no choice but to take refuge in a neutral port.