State Route 339 (SR 339) is a 8.5-nautical-mile-long state highway in the U.S. state of Washington. It is designated on a former state-run ferry route that connected Vashon Island's Vashon Heights ferry terminal to downtown Seattle's Pier 50, via a passenger-only ferry, the MV Skagit. The ferry was financed by the King County Ferry District (KCFD) and tolls collected at Pier 50. Despite being part of the KCFD, the ferry was operated by Washington State Ferries (WSF). SR 339 was one of only four ferry routes providing access to and from Vashon Island, and had the lowest annual average ridership of the four routes. The state of Washington took over the operation of the ferry route in 1951, and designated it SR 339 in 1994. The ferry was discontinued in 2006 and was replaced by a King County Water Taxi route.

State Route 160 (SR 160) is a 7.47-mile-long (12.02 km) long state highway serving Kitsap and King counties in the U.S. state of Washington. The highway begins at an interchange with SR 16 in Port Orchard and travels east to the Southworth ferry terminal, where the route continues onto a ferry to Vashon Heights, the former southern terminus of SR 339, and further east to end at the Fauntleroy ferry terminal in Seattle.