HMS D1 was one of eight D-class submarine built for the Royal Navy during the first decade of the 20th century.

[1] The D-class submarines had a crew of 25 officers and ratings and were the first to adopt saddle tanks.

[2] For surface running, the boats were powered by two 600-brake-horsepower (447 kW) diesels, each driving one propeller shaft.

On the surface, the D class had a range of 2,500 nautical miles (4,600 km; 2,900 mi) at 10 knots (19 km/h; 12 mph).

[3] The wreck was discovered by divers looking for the remains of German U-Boats and has been afforded protected status.