STORY: People waded far out into the river as boats were forced to navigate on a narrow channel in the middle, kept open only by dredging the riverbed.
Normally, the stretch navigable by large boats is several hundred metres wide at Novi Sad, Serbia's second-largest city.
The Danube, one of the longest rivers in Europe, is a trade and transport artery that passes through ten countries.
The low water levels are also threatening fish stocks in the river, according to Marija Trivuncevic, a spokeswoman for a local angling association.
"The circumstances are dire," Trivuncevic said, adding the situation was likely to get worse as channels from the Danube used for watering crops also dry out.
Even rainfall might pose a threat to fish in the river, she said, as it could reduce the oxygen content in the water and kill local wildlife.