The Hải Vân Pass (, ], ocean cloud pass), is an approximately 21 km long mountain pass on National Route 1A in Vietnam. It traverses a spur of the larger Annamite Range that juts into the East Sea of Viet Nam, on the border of Đà Nẵng and Thừa Thiên-Huế Province, near Bạch Mã National Park. Its name refers to the mists that rise from the sea, reducing visibility. Historically, the pass was a physical division between the kingdoms of Champa and Đại Việt.