The 47-year-old festival-goer had gone for a swim late Sunday evening with his girlfriend, who called police when he failed to surface.

“According to information from his partner they had both consumed alcohol at the festival,” police spokesman Patrick Maierhofer told the ORF.

The police also said that the girlfriend had tried to pull her boyfriend out of the water when she realised he had got caught up in a whirlpool but had been unable to rescue him.

Paramedics on the scene were also unable to revive him.

It followed an incident earlier on in the evening when one witness said they saw a Somali man jump from Brigittenau Bridge into the water near Neue Donau U-Bahn station.

Others said it looked like an accident as they thought man had not wanted to go completely in the water but then fell in and went under.

The 19-year-old was rescued by divers and brought to hospital but died later that night.

Witnesses reported seeing an emergency helicopter try to land on the water near the bridge as well as dozens of ambulances on the Donau Island.