HMS A1
HMS A1 is a British Royal Navy submarine that rests on the seabed approximately two miles off the coast of Selsey Bill in West Sussex, England. It is one of the most historically significant submarine wrecks in British waters, as she was the Royal Navy's first purpose-built submarine and a pioneering vessel in the early development of underwater warfare. For recreational divers, the wreck represents a rare opportunity to explore a piece of genuinely epoch-making naval history, lying in relatively accessible shallow water that makes her suitable for a range of diving experience levels.
The A1 was completed in 1902 at Barrow-in-Furness by Vickers, Sons and Maxim, and entered service as the lead boat of the A-class submarines. She met her end on 18 March 1904 in catastrophic circumstances during a training exercise in the Solent. While running on the surface, she was struck by the passenger liner SS Berwick Castle. The collision caused her to sink almost immediately, and all eleven crew members aboard were lost. It was the Royal Navy's first submarine disaster, and it sent shockwaves through the nascent submarine service at a time when the Admiralty was still trying to convince both the public and senior naval officers of the viability of submarines as serious weapons of war. The tragedy drew enormous attention to the risks faced by early submariners, often called the "trade" by those who served in them.
Following the sinking, the wreck was salvaged later in 1904 and the submarine was returned to service after repairs, a remarkable feat of early marine engineering. She continued to serve the Royal Navy for several more years, but fate was not done with her. In 1911, HMS A1 was being used as an unmanned experimental target vessel, testing early remote-control technology. During one such test, she sank a second and final time in the waters off Selsey Bill, this time settling permanently on the seabed where she remains to this day. This second sinking, while undramatic compared to the first, gave her a unique dual place in history as both a casualty of collision and a subject of early remote-control experimentation.
The wreck today lies at a depth of around 18 metres, oriented roughly northeast to southwest on a sandy seabed. The hull is largely intact in outline but heavily encrusted with marine growth, with anemones, sponges, and various encrusting organisms having colonised the steel over more than a century. Visibility can vary considerably depending on tidal conditions and the time of year, but on a good day divers can take in the full silhouette of the narrow, cigar-shaped hull, which measures approximately 30 metres in length. The conning tower stub and various external fittings remain distinguishable to experienced eyes, and the surrounding seabed is scattered with small debris from the wreck's long residence in the water.
The area around Selsey Bill and the waters between the Bill and the Isle of Wight are rich in maritime heritage. The coastline here is part of the coastal fringe of the Chichester Harbour Area of Outstanding Natural Beauty, and the town of Selsey itself is a quiet seaside settlement with strong fishing traditions. To the east lies Bognor Regis, and to the north is the cathedral city of Chichester with its famous harbour and Roman heritage. The waters off Selsey are popular with local divers, and several dive operators in the region offer charter trips to the A1 and other wrecks in the area.
Divers wishing to visit the wreck will typically need to arrange passage on a charter dive boat operating from Selsey, Chichester Harbour, or nearby ports. The dive is generally considered suitable for sports divers with open water certification and some wreck diving experience, though tidal conditions must be respected as currents in the area can be strong. The best diving conditions are typically found around slack water, and summer months offer better visibility and more comfortable sea temperatures. The wreck is protected under the Protection of Military Remains Act 1986, which means that while diving around the exterior is permitted, penetration of the wreck or disturbance of any material is strictly prohibited.
HMS A1 holds a peculiar double distinction that few wrecks anywhere in the world can claim. She sank not once but twice, survived to serve again after the first sinking, and ultimately became an inadvertent pioneer of drone technology decades before the concept existed in any recognisable form. The loss of her crew in 1904 also prompted significant improvements in submarine design and safety procedures, meaning that her tragedy contributed directly to the survival of future generations of submariners. For anyone with an interest in naval history, the early submarine service, or pioneering technology, she is an extraordinarily evocative and layered site.