The Hai Van Pass
(Vietnamese: Đèo Hải Vân, IPA: [ɗɛ̂w ha᷉ːj vən], “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 South China Sea, 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. The twisting road on the pass has long been a challenge for drivers traveling between the cities of Huế and Đà Nẵng. Since the completion of Hải Vân Tunnel, traffic flow and safety have improved.
