The Mosi Tunnel is a motorway tunnel in Switzerland which opened in 1964. It is situated on the A4 and also the main part of the bypass of Brunnen SZ which leads between Brunnen North and Brunnen South. The two lane tunnel (one lane for each direction) is 1100 metres long and links the motorway A4 with the Axenstrasse. It is the longest road tunnel in the Canton of Schwyz and will be until the Morschacher Tunnel opens in 2020 between Brunnen North and Sisikon.