Robert Dawson of the Nautical Archaeology Society reports on a new initiative, WRECKognising Pollution, which aims to monitor wrecks for signs of dangerous leaks
UKDIVING
Unexploded munitions on the Thistlegorm wreck, Egypt
Shipwrecks: a toxic legacy
Robert Dawson of the Nautical Archaeology Society reports on a new initiative, WRECKognising Pollution, which aims to monitor wrecks for signs of dangerous leaks
The waters around the UK contain some of the highest concentrations of shipwrecks in the world. This legacy comes from two world wars, numerous smaller conflicts, and centuries of maritime trade. As a result, the UK offers exceptional wreck diving opportunities, from historic wooden ships to modern steel cargo vessels that have come to grief.
The environmental impact of shipwrecks is often all too visible. Earlier this year, Storm Goretti led to multiple shipping containers being lost into the sea and washed ashore along the South Coast. As they broke apart, their contents and foam insulation was scattered for miles, leading to extensive coastal pollution. This cost West Sussex County Council £ 2.7 million to clean up, as well as the efforts of local volunteers – many from dive clubs – seeking to protect our seas.
Such incidents attract attention and action. However, we as divers often overlook a much less visible problem: the toxic legacy hidden within the shipwrecks themselves.
Many wrecks contain hazardous materials such as fuel oil, munitions and unexploded ordnance, plus toxic paints, mercury, and chemicals from onboard equipment. As wrecks corrode, these substances can leach into the marine environment. Some are toxic or even carcinogenic, posing longterm risks to ecosystems and coastal communities.
This risk is particularly significant when it comes to wrecks dating from the Second World War. Unlike earlier vessels powered by wind or coal, WWII ships relied primarily on oil and carried munitions. Now, nearly 90 years on, many of these wrecks are reaching a critical point in their deterioration.
Many losses are undocumented, making it hard to identify where pollution risks may be
Leaking wrecks
In September 2025, a state of emergency was declared in the State of Chuuk, a popular diving destination, after the Japanese shipwreck Rio de Janeiro Maru started leaking oil, clearly visible as a slick from the surface. In Chuuk lagoon alone, there are 17 other wrecks understood to pose a significant threat.
Closer to home off Selsey Bill is the‘ Tanks and Bulldozers’ wreck site, lost on the night of 5 / 6 June 1944 when a landing craft capsized under tow in the Solent, after breaking down on route to the D-Day landings in Normandy. The seabed around the tanks is covered with high explosive shell casings and other munitions. Other wrecks in the Solent and English Channel area contain visible, decaying depth charges, and the presence of white phosphorus is a recognised risk.
40
' Sunken Ships of the Second World War’ database by Paul Heersink. Blue dots represent Allied ships; red dots are Axis