The Kerenzerberg Tunnel is a motorway tunnel in Switzerland, and forms part of the A3 motorway from Basel to Sargans. The tunnel is approximately 5.8 km long and it lies southwest of Lake Walen.
The Kerenzerberg Tunnel is a one-way, unidirectional tunnel. Traffic from Zurich to Sargans must pass through the Kerenzerberg Tunnel, in the opposite direction the motorway runs along the shores of the Walensee through six short tunnels originally built for a railway. The railway now run through a 4 km tunnel. Transportation of dangerous goods through the Kerenzerberg tunnel is prohibited.