Juan de Fuca Strait is an inlet of the Pacific Ocean between Vancouver Island and Washington State, connecting the Strait of Georgia and Puget Sound to the outer ocean. The international boundary with the US follows its 160 km length. It is one part of the inland marine sea, the Salish Sea.

Tides are complicated and dangerous for ships using it to approach mainland harbours. It was named for mariner Juan de Fuca, whose voyages to the area were likely apocryphal. In 1787, the trading captain Charles Barkley entered the strait and named it. Until George Vancouver's explorations in the early 1790s proved otherwise, Juan de Fuca Strait was considered a possible entrance to a northeastern passage to the Atlantic (see also Strait of Anian).