Wrecks were from Adolf Hitler's Black Sea fleet, which the German military deliberately sank, historians sayThis advertisement has not loaded yet, but your article continues below. Create an account or sign in to continue with your reading experience. Nazi warships and human remains have been exposed in the Danube River more than 80 years after the Second World War as the waterway has receded due to a record heatwave. Attempts were made by past Serbian governments to remove the shipwrecks, but the presence of explosives delayed those efforts. Photo by Handout / German War Graves Commission / AFP / Getty ImagesDangerously low water levelsThe Danube, which flows through 10 nations, has seen its waters recede this summer to dangerously low levels, which has impacted shipping traffic this summer.