‘Environmental time bombs’: Risks from wartime wrecks prompt global warning
The wreck of HMS Cassandra, as surveyed by HMS Echo in 2021. Image courtesy of Imperial War Museum.
An international coalition has issued a call to address the potentially ‘catastrophic’ environmental risks posed by thousands of wartime shipwrecks located across the world’s oceans.
“We have thousands of environmental time bombs ticking on our ocean floor, with billions in remediation costs and no dedicated funding mechanism,” says Mark J. Spalding, president of The Ocean Foundation.
Released on 12 June 2025, during the third UN Ocean Conference, The Malta Manifesto outlines a framework for action and urges the formation of a dedicated international finance task force to support mitigation efforts. The initiative is led by Project Tangaroa, coordinated by Lloyd’s Register Foundation, The Ocean Foundation and Waves Group.
Potentially polluting wrecks
Estimates suggest that at least 8,500 potentially polluting wrecks (known as PPWs) remain on the seabed, mostly dating back to World War I and World War II. The true figure is likely to be higher. These wrecks are distributed globally, from the Baltic and Mediterranean to the Arctic, Caribbean and Latin America, with a particular concentration in the South Asia-Pacific region. The coalition notes that many of the affected coastal and island nations do not have the necessary resources to manage the associated risks.
These wrecks typically contain oil and hazardous materials, including munitions, and are increasingly unstable due to factors such as ocean acidification and more frequent storms. Several are already leaking, with implications for marine ecosystems, fisheries and communities.
“The bureaucratic luxury of slow responses doesn’t match the environmental urgency – we need a Finance Task Force with the authority to act before 2039,” says Spalding.
The Malta Manifesto sets out seven recommendations aimed at governments, industry, researchers and civil society. These include actions on financing, standards, planning, innovation, training and data sharing. The goal is to implement coordinated and precautionary measures ahead of the centenary of the start of World War II in 2039.
The manifesto highlights earlier interventions as potential models for wider efforts. One such case involves the wreck of HMS Cassandra, a British cruiser sunk in 1918 near Saaremaa, Estonia. Responding to concerns raised by the Estonian government, the UK Ministry of Defence’s (MOD) Salvage and Marine Operations (SALMO) team is conducting a detailed survey in partnership with Waves Group.
“PPWs pose a great global threat to coastal communities and marine ecosystems,” says Lydia Woolley, Project Tangaroa programme manager at Lloyd’s Register Foundation. “Left unmanaged, they could result in the destruction of vital fishing grounds and coastal tourism, with devastating effects on the marine environment, human health and wellbeing, as well as local and regional economies.
“However, our message is not fatalistic – it is one of urgent encouragement. Thanks to the work of the global community of experts brought together by Project Tangaroa, we already know how to manage the risks posed by these wrecks – but we need the resources to put this knowledge to use at the required scale.”
Simon Burnay, chief executive of Waves Group, says: “Collectively, we have the proven experience and methodologies for assessing and reducing the risks posed by PPWs. An internationally accepted standard will help scale these capabilities globally, providing funders with the assurance needed to have a lasting positive outcome for future generations.”
A central proposal in the manifesto is the establishment of an international PPW Finance Task Force to coordinate funding efforts across public, private and philanthropic sectors.
Matt Skelhorn, head of the UK MOD Wreck Management Programme at DE&S SALMO, says: “With the survey of the Cassandra, we’re already putting into action the proof of concept for the Malta Manifesto. We look forward to sharing the survey outputs in due course, which will inform how we continue to work with the Estonian government to take action to prevent oil leakage if required. Cassandra has the potential to become a blueprint for future international collaboration when it comes to addressing the risks caused by PPWs.”
SALMO manages over 5,000 wrecks once under MOD ownership and has supported Project Tangaroa since its inception.
“The Malta Manifesto is a critical step towards the appropriate management of PPWs across the world. It clearly articulates the risks posed, and the vital need for international collaboration and agreed standards, as well as enhanced resilience, response capacity and local empowerment to address this globally significant challenge,” says Skelhorn.
On 11 June, the International Council on Monuments and Sites (ICOMOS) and the International Union for Conservation of Nature (IUCN) submitted a statement to the UN Environment Programme calling for urgent action on PPWs.
“ICUCH is fully supportive of the Malta Manifesto: it provides clarity on the risks and consequences of PPWs and describes a roadmap aimed at promoting preventative action, rather than facing the very real alternative possibility of hugely damaging oil spills,” says Dr Christopher Underwood, president of the ICOMOS International Committee on the Underwater Cultural Heritage.
“The timely example of HMS Cassandra reminds us that many of these wrecks are also the last resting place of some or all of their crews. As such, the utmost care must be taken to minimise their disturbance during surveys and interventions. The Malta Manifesto, critically, recognises this and other management issues that reveal a complexity in addressing both natural and cultural perspectives.”
Not all shipwrecks pose environmental concerns. A recent study conducted by the University of Plymouth and Blue Marine Foundation has shown that the estimated 50,000 shipwrecks found around the UK’s coastline have been acting as a hidden refuge for fish, corals and other marine species in areas still open to destructive bottom-towed fishing.
