Тхыатхьен-Хюэ
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.