Beneath the waters off Germany’s northern coastline, a legacy of the Second World War continues to pose a slow-burning environmental threat. Vast quantities of unexploded munitions, discarded on the seabed decades ago, are now corroding and releasing potentially hazardous substances into the marine ecosystem.
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Scientists warn that as saltwater gradually erodes the metal casings of bombs, shells and rockets, toxic compounds such as TNT could seep into surrounding waters. Concern has intensified in areas such as Kiel, where the seabed is among the most heavily contaminated.
In response, researchers from Germany, Poland and Lithuania have embarked on a three-week expedition aboard the research vessel Alkor, operated by GEOMAR Helmholtz Centre for Ocean Research Kiel. Their mission is to map the extent of the hazard and explore potential methods for safe removal. Led by marine scientist Aaron Beck, the team is employing underwater robots and sampling equipment to examine sediment, water and marine life. Mussels are being deployed and later retrieved to assess contamination levels, offering insight into how pollutants may be entering the food chain.
The scale of the problem is considerable. Along Germany’s Baltic coast alone, an estimated 1.6 million tonnes of munitions lie scattered across the seabed, much of it dumped hastily by Allied forces following the country’s surrender in 1945. Over time, traces of carcinogenic substances have been detected in shellfish and other marine organisms.
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The semi-enclosed nature of the Baltic Sea exacerbates the issue. With limited exchange with the open ocean, pollutants tend to accumulate rather than disperse, raising concerns for long-term ecological health.
While researchers emphasise that current contamination levels pose no immediate risk to human health, they caution that the situation requires close monitoring. Beck noted that a person would need to consume unusually large quantities of contaminated fish over an extended period to face significant exposure.
Beyond munitions, sunken vessels themselves present an additional hazard. Some wrecks contain far greater quantities of fuel than ammunition, increasing the risk of oil leakage. One such case is the tanker German tanker Franken, sunk in 1945 and still believed to hold substantial reserves of fuel. Efforts are under way to address the problem. Germany has initiated a pilot project in Lübeck Bay, where specialised platforms are being used to safely dispose of underwater munitions. The scheme, backed by significant public funding, has already involved divers and robotic systems clearing several sites.
However, the long-term outlook remains uncertain. The sheer scale of the contamination, combined with legal and financial complexities, means that a comprehensive solution has yet to be secured. As offshore development expands — from wind farms to telecommunications infrastructure — the urgency of addressing these submerged hazards is likely to grow, bringing renewed attention to a problem that has lingered beneath the surface for nearly eight decades.
