In pictures: What one of the world's greatest rivers kept hidden — until now

The Danube River, the second-longest in Europe, has seen its water levels drop to record lows due to a severe drought. This has revealed the remains of numerous World War Two German warships, including those from Nazi Germany's Black Sea fleet, which deliberately sank to impede the Soviet advance in the Balkans in September 1944.

The ships, some still carrying weapons, have become both a curiosity and a reminder of the past. Efforts to conserve energy and maintain river traffic have intensified as water levels recede, posing risks to power plants and navigation. The Serbian government, with EU support, has long sought to address these remnants, though many remain due to the explosives they carry.

Meanwhile, the low water levels have also led to the exposure of human remains, including those of two German soldiers and potentially an ancient mammoth, highlighting the river's unique ability to expose history buried beneath its surface.