The Untersee, or Lower Lake, which is separated from the Obersee and from its north-west arm, the Überlinger See, by the large peninsula of Bodanrück, has an area of . It is strongly characterised and divided into different areas by end moraines, various glacial snouts and medial moraines. These various areas of the lake have their own names. North of Reichenau Island is the Gnadensee. West of the island of Reichenau, between the peninsula of Höri and the peninsula of Mettnau is the Zeller See (or Zellersee in Swiss Standard German), or Lake Zell. North of the peninsula and swamp land Mettnau lies the lake part Markelfinger Winkel. The drumlins of the southern Bodanrück continue along the bed of these northern parts of the lake. South of the Reichenau, from Gottlieben to Eschenz, stretches the "Rheinsee" (lit.: "Rhine Lake") with strong Rhine currents in places. Previously this lake part was named Lake Bernang after the village of Berlingen. On most of the maps the name of the "Rheinsee" is not shown, because this place is best suited for the name of the Untersee.