HMS H4 was a British H-class submarine built by the Canadian Vickers Co., Montreal.

[3] The use of its electric motors made the submarine travel at 11 knots (20 km/h; 13 mph).

British H-class submarines had ranges of 1,600 nautical miles (3,000 km; 1,800 mi).

[2] H4 was fitted with a 6 pounds (2.7 kg) Hotchkiss quick-firing gun (6-pounder) and four 18 inches (460 mm) torpedo tubes.

[2] It is a Holland 602 type submarine but was designed to meet Royal Navy specifications.