[Note 1] In 6 patrols UC-18 was credited with sinking 34 ships, either by torpedo or by mines laid.

She had a dive time of 35 seconds and was capable of operating at a depth of 50 metres (160 ft).

When submerged, she could operate for 55 nautical miles (102 km; 63 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 9,430 nautical miles (17,460 km; 10,850 mi) at 7 knots (13 km/h; 8.1 mph).

UC-18 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.

[3] In March 2024, it was announced that the wreck of UC-18 had been discovered by a team of divers off the island of Guernsey at a depth of 70 m (230 ft), some 64 km (40 mi) further west than the historical accounts of the battle described which was originally believed to have been 13 km (8 mi) west of the coast of Jersey.