Severe drought has pushed water levels on the Danube River—Europe's second-longest waterway—to record lows, exposing the rusted hulks of dozens of World War II-era German warships that had long rested beneath the surface.

The emerging wrecks, visible near the Serbian port of Prahovo along the river that separates Serbia and Romania, include a broken mast where the Nazi flag once flew. The ships belonged to Nazi Germany's Black Sea fleet, deliberately scuttled by retreating German forces as Soviet troops advanced deeper into Europe toward the end of the war. Some of the vessels remain laden with weapons and explosives.

Historians estimate that up to 200 German warships were sunk in September 1944 near Prahovo in the Danube gorge while under Soviet fire. The deliberate scuttling was intended to slow the Soviet advance through the Balkans. Nazi Germany ultimately surrendered in May 1945, just months later.

The wrecks have surfaced periodically during past droughts, including in 2003, 2012, and 2018, each time briefly drawing attention to the unresolved hazard before water levels rose again.

The Serbian government, with financial backing from the European Union, has long sought to address the wreckage. Communist Yugoslav authorities previously removed some vessels, but most remained in place due to the explosives they carried.

Beyond the historical spectacle, the Danube's receding waters are creating pressing infrastructure challenges. The river is a critical commercial artery for Central and Eastern Europe, carrying grain, coal, fuel, and other bulk goods to and from Black Sea ports. Record-low levels have brought power plants to the brink of shutdown, prompting governments across the region to implement electricity conservation measures. The Danube flows through 10 nations, and authorities are now working to maintain river traffic as shrinking channels create hazardous navigational conditions. The disruption echoes similar low-water crises on the Rhine in 2022, when drought grounded cargo across one of Western Europe's key trade routes.

Experts have attributed the extreme heat to global warming and other contributing factors. European summers have grown progressively hotter and drier over the past two decades, intensifying pressure on river systems that serve as both transport corridors and cooling sources for industry.

Krsta Brandic, a resident of Prahovo, described the impact on local shipping: "As you can see, the (big) ships can't pass anymore."

Associated Press writer Dusan Stojanovic contributed reporting from Belgrade, Serbia.

This story was originally featured on Fortune.com.