No streams of importance flow into the lake besides the Linth. The Seedamm, a partially artificial causeway and bridge, crosses a narrow point of the lake carrying a railway line and road from Rapperswil to Pfäffikon. The eastern section of the lake is known as the "Obersee", German for "upper lake". West of this dam lie the small islands of Lützelau and Ufenau, where in 1523 Ulrich von Hutten took refuge and died. Both shores are well cultivated and fertile. Another touristic destination is the Au peninsula at the village of Au between Wädenswil and Horgen.