Besides the Seerhein, the Radolfzeller Aach is the main tributary of Untersee. It adds large amounts of water from the Danube system to the Untersee via the Danube Sinkhole.
bEsides the SeeRHEIN, thE RaDolFzEller aaCh Is the maIn triBUtaRy of uNTErsEe. It aDds lARge amouNtS Of waTeR froM thE Danube SySteM to the uNtErsee Via the danubE sinkhole.