Germany tackles explosive wartime legacy at sea – DW – 06/14/2025

DW

14-06-2025

Unexploded WWII bombs are still regularly found across Germany. But hundreds of thousands of tons of wartime munitions also lurk off its shores. Now Berlin is stepping up moves to clean up this perilous toxic waste.
An estimated 1.6 million metric tons of conventional munitions lie in Germany's coastal waters alone. The vast majority is located in the North Sea; the rest in the Baltic. There are also thought to be several thousand tons of chemical weapons.
Most have lain largely forgotten for 80 years or more. While headline-grabbing bomb discoveries on dry land close down entire neighborhoods and transport networks, as in the western German city of Cologne in early June, the threat is much more insidious at sea.
Growing fears over contamination have prompted action. Now, a large mobile platform is planned that will autonomously retrieve old weapons from the seabed and dispose of them. The trailblazing project was presented to the international community at the UN Ocean Conference in the French city of Nice in June.
"Up to now, recovery operations were only carried out in the event of imminent danger, if, for example, an undetonated bomb was at risk of exploding," said Sebastian Unger, marine conservation director at Germany's Environment Ministry (BMUKN).
"Now, it is about finally tackling this problem for reasons of environmental and marine conservation, but also to ultimately reduce human health risks," added the ministery expert, talking to DW from the event.
Saltwater corrosion has rusted munition casings causing them to leak TNT Image: GEOMAR
TNT released by dumped WWII munitions
German mines and explosives discarded by Allied bombers on their way back to Britain are among the WWII combat weapons strewn across the ocean floor. But most of the explosives in Germany's North Sea and Baltic waters ended up there after the defeat of Nazi Germany in 1945.
British troops tipped the armaments that they found in weapons factories and warehouses into the sea. It was seen as a quick fix in the process to denazify and demilitarize Germany.
In recent years, it has become apparent that they are decomposing. One visible sign of their decay is lumps of white phosphorus or an explosive mixture containing TNT occasionally washing ashore. The substances look frighteningly similar to prize amber or minerals and visitors and beachcombers have been injured.
Amber is regularly found at the Baltic but white phosphorus can look quite similar Image: Andreas Franke/picture alliance
Carcinogenic toxins affecting marine life
Toxicological tests carried out on mussels in the dumping site over the last decade have revealed traces of carcinogenic chemicals contained in the munitions. Examination of samples gathered since the 1980s also show a steady rise from 2002 onwards.
"The concentrations are very, very low. As humans we don't have to be concerned about eating these mussels. But if we go further down the line — maybe in 30, 40 years — we might have to think twice," said Edmund Maser, a toxicologist from the University Hospital of Schleswig-Holstein (UKSH), who has been involved in the research.
The marine ecosystem is, however, already at risk, according to Maser. TNT traces have been found in fish and in seawater, too. And as the metal casings surrounding the munitions continue to rust, ever more will be released.
GEOMAR detected munition strewn across the Bay of Lübeck in the Baltic Sea Image: Geomar/dpa/picture alliance
Explosives piled up like Mikado sticks
GEOMAR, the Helmholtz Center for Ocean Research in Kiel, was asked by the Schleswig-Holstein state government in 2016 to help find out what weapons were down there and their possible environmental impact.
They have been using a variety of acoustic and visual technologies, which they have continued to develop during the ongoing pilot phase. The results have been mind-boggling.
"There is munition there, crates of it. One area is 20 by 40 meters in size where munition boxes are stacked up on the seabed, as if they've just been unloaded from a truck. In another spot there were a lot of bombs, 50 to 250 kilogram bombs, piled up like Mikado sticks," Jens Greinert, GEOMAR marine geologist, told DW. Small caliber ammunition, pistols and rocket launchers were also discovered.
The challenges of the shifting marine environment and the sheer mix of munitions on the seabed make the recovery process complicated as well as hazardous. The material inside can still explode — and there is always the risk of the release of toxic chemicals, such as TNT, during the retrieval and disposal process. GEOMAR and UKSH will also be part of the team monitoring the clean-up.
With autonomous underwater vehicles like these, GEOMAR can make photographic charts of the seabed Image: Julia Gehringer/GEOMAR
Ticking time bomb
German environmental organization NABU began drawing attention to the problem in 2007 and is calling for the clean-up operation to get underway as soon as possible.
"We don't really have a lot more time. The decomposition is, in part, at a more progressed stage than we were hoping. Of course, the problem exists on land, too. But toxins remain localized there, while in the sea they continue to spread and enter the food chain," Kim Detloff, NABU head of marine conservation, said in an interview with DW.
The NABU expert said there remained a problem with ongoing financing of the long-term operation of the planned platform. "It needs to be working 365 days 24/7," said Detloff. And he added that the enormous scale of the problem meant that far more than one floating platform was needed.
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Technology transfer to other contaminated marine areas in the world
The pilot and next phase of the munitions recovery project were financed with a €100 million emergency program from the federal government.
The groundbreaking salvaging and dismantling platform should be ready for deployment by late 2026 or early 2027, according to the BMUKN's Unger. He hopes such approaches will be adopted in other parts of the world.
In German waters, operations are likely to prioritize particularly ecologically sensitive areas, fish spawning grounds or areas close to the coast that are of particular interest to the tourist industry, but that is still under consideration, according to Unger.
Edited by Helen Whittle
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