The Hải Vân Pass (Vietnamese: Đèo Hải Vân, "ocean cloud pass"), is an approximately 21km long mountain pass on National Road 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 Bach Ma 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 Dai Viet.
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 Hai Van Tunnel, traffic flow and safety have improved. The pass has been the scene of at least two of Vietnam's most serious rail accidents, and at least one air crash.