HMS C7 was one of 38 C-class submarines built for the Royal Navy in the first decade of the 20th century.

[1] For surface running, the boats were powered by a single 16-cylinder 600-brake-horsepower (447 kW) Vickers petrol engine that drove one propeller shaft.

On the surface, the C class had a range of 910 nautical miles (1,690 km; 1,050 mi) at 12 knots (22 km/h; 14 mph).

They could carry a pair of reload torpedoes, but generally did not as they would have to remove an equal weight of fuel in compensation.

[3] C7 was built by Vickers at their Barrow-in-Furness shipyard, laid down on 9 December 1905 and was commissioned on 23 May 1907.