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Wreck of WW1 cruiser lost in Baltic could hold key to tackling environmental timebomb
12 June 2025
Work on a Royal Navy WW1-era shipwreck could serve as the blueprint for nations tackling a hidden environmental timebomb left by the World Wars.
What experts learn from the state of cruiser HMS Cassandra – lost off the Estonian island of Saaremaa in December 1918 after hitting a mine – will inform how her wreck is managed, as experts determine how much oil and other pollutants could still be on onboard.
The pioneering work with Cassandra will hopefully constitute one more step towards reducing the risks posed by the Royal Navy’s inventory of potentially-polluting wrecks.
It’s thought there are around 8,500 wrecks from the 20th Century’s global conflicts.
The pollutants remaining within theseis haves the potential to cause catastrophic damage to coastal communities and marine life, whether it’s oil escaping from the shattered hulks or the poorly-understood risks posed by chemicals leaching from ammunition.
As part of the third United Nations Ocean Conference, Project Tangaroa – a global community of experts coordinated by Lloyd’s Register Foundation, The Ocean Foundation and Waves Group – called on governments to act decisively before the situation becomes critical.
The Tangaroa team warn that after 80 to 110 years beneath the waves, all are becoming increasingly unstable – their state made worse by the impacts of climate change such as increased storms and ocean acidity.
Some are already leaking oil into the oceans, putting marine ecosystems, vital fishing grounds and vulnerable coastal communities at risk.
HMS Cassandra was bound for Tallinn to support the Estonians’ efforts to break away from Bolshevik rule at the end of the Great War only to strike a mine. Most of her 400 crew survived, but 11 went down with the cruiser, whose wreck lies in around 100 metres of water.
HMS Echo surveyed the site four years ago, but now a far more detailed study is being conducted by the MoD’s Salvage and Maritime Operations team (SALMO), who manage the MOD-owned inventory of potentially-polluting wrecks on behalf of Navy Command, and Waves Group.
Matt Skelhorn, Head of the UK MOD Wreck Management Programme at DE&S SALMO, said the findings would be shared widely, as the UK worked with the Estonian authorities to ensure the Baltic was not saubjected to oil leaking from an MOD wreck.
He continued: “HMS Cassandra has the potential to become a blueprint for future international collaboration when it comes to addressing the risks caused by potentially-polluting wrecks.”
Project Tangaroa has SALMO Wrecks team engage with the appropriate authorities around the world to better manage the RN inventory of MOD-owned wrecks..
SALMO has been closely involved with Project Tangaroa since its inception, providing critical insights on the practical and political challenges involved with the management of its own inventory of more than 5,000 wrecks around the world.
Mr Skelhorn welcomed the ‘call to action’, which was published last month in a document known as The Malta Manifesto.