The Rapperswil Seedamm is the artificial causeway at the narrowest area of Lake Zurich between Hurden (SZ) and Rapperswil (SG). The structure contains two bridge segments and is approximately 1 kilometre (0.62 mi) long. The Seedamm carries a road (Hauptstrasse 8) and a railway across the lake, with the railway being used by the S5 and S40 services of Zurich S-Bahn and by Südostbahn's Voralpen Express.

The Melide causeway across a narrow section at Lake Lugano is comparable to the Seedamm.

The Seedamm connects the Swiss cantons of Schwyz (Hurden) and St. Gallen (Rapperswil).