The Schwimmtor (Floating gate), also known as the Sperrschiff (Blocking ship), was a floating barrier designed to protect the areas along the Donaukanal in Vienna from flooding and ice. It was built by Wilhelm von Engerth, entered service on 13 December 1873, and was scrapped following World War II.
The Schwimmtor was located 166 metres downstream of the Brigittenauer Spitz. The site was chosen because the canal was thin enough at this point that the floating barrier could withstand the pressure which would be caused by an accumulation of floodwater or ice.
A rounded indentation was carved into the left-hand (Brigittenau) quay wall, where the Schwimmtor was to be stowed when it was not needed. Just downstream of this indentation, the quay wall jutted out into the middle of the canal, thereby forming a support against which the barrier could be placed when it was needed.
Supporting the barrier with the same sort of elongated wall on the right-hand (Nussdorf) bank,