The Danube loop is a flow loop in the Upper Danube Valley in Upper Austria, about halfway between Passau and Linz (between river kilometers 2180.5 and 2186.5 of the Danube). The southern shore is in the municipality of Haibach ob der Donau and its district Schlögen, which gives the name of the loop. In the north the municipalities bordering Hofkirchen im Mühlkreis with the village of Au and in the far east Niederkappel with the town of Grafenau in the Donauschlinge.

source: https://de.wikipedia.org/wiki/Schlögener_Schlinge