|Launched:||9 December 1915|
|Commissioned:||9 January 1916|
|Fate:||Sunk by mine on or about 24 March 1916|
|Class and type:||E-class submarine|
|Displacement:||662 long tons (673 t) surfaced
807 long tons (820 t) submerged
|Length:||181 ft (55 m)|
|Beam:||15.05 ft (4.59 m)|
2 × 1600 hp Vickers diesel
2 × 840 hp electric motors
2 × screws
|Speed:||15 knots (28 km/h; 17 mph) surfaced
10 knots (19 km/h; 12 mph) submerged
|Range:||3,000 nmi (5,600 km) at 10 kn (19 km/h; 12 mph) surfaced
65 nmi (120 km) at 5 kn (9.3 km/h; 5.8 mph) submerged
|Armament:||• 5 × 18 in (457 mm) torpedo tubes (2 bow, 2 beam, 1 stern)
• 1 × 12-pounder gun
E24 belonged to the Harwich-based 9th Flotilla at the time of her loss. She was the second E-class boat to be converted into a minelayer. E24 left Harwich on the morning of 21 March 1916 to lay mines in the Heligoland Bight. A positional report was issued late that night. Her commander, Lieutenant-Commander Naper, was ordered to enter the Bight in darkness on the surface via the Amrum Bank. Once in position he was to lay mines in a zigzag formation. As mines were known to have been laid by the Germans off Ameland, Naper was ordered to return by the same route. She did not return from the mission, and was logged as missing on 24 March 1916.
Divers hunting for a Second World War-era U-boat in 1973 raised sections of a mined submarine wreck, including the conning tower. The boat was towed to Cuxhaven where the wreck was identified as a British E-class boat, rather than a German submarine. The German government then informed the Admiralty.
Human remains found in the wreck are buried in Ohlsdorf Cemetery, Hamburg. E24 's commander is buried in a separate grave to others. Lieutenant-Commander Naper was identified because of the 2+half rings on sleeve, and the fact that his skeleton was 6 ft tall. All the skulls of those in the boat were found in a pyramidal formation. The sunken wreck lay at a downward angle, causing the heads to become detached from the bodies and to roll down the slope into that position. Three bodies were found lying under the battery boards directly on top of the batteries, with arms folded. They may have died of the effects of chlorine gas before the rest of the crew. Artefacts from E24 and her crew, such as smoking pipes belonging to Naper, a bottle of blackberries, the sextant, a firing pistol and boots are on display at Cuxhaven, as are the submarine's conning tower and propellers.
- Hutchinson, Robert, Submarines, War Beneath The Waves, From 1776 To The Present Day