State Route 108 (SR 108, also known as the Old Olympic Highway) is a state highway in Grays Harbor and Mason counties, of the U.S. state of Washington. It extends from SR 8 in the city of McCleary, east to an interchange with U.S. Route 101 (US 101) in Kamilche. The route serves as a bypass and connects McCleary with Shelton, and Port Angeles.