O Quy Ho Pass is a mountain pass in the long pass, rugged and most majestic in mountainous northern Vietnam. Located on National Highway 4D cross Hoang Lien Son mountain pass connecting the two provinces of Lao Cai and Lai Chau to the top of the pass is also the boundary between the two provinces. O Quy Ho Pass also known as Hoang Lien Son Pass by pass Hoang Lien Son mountain range, or the Pass Cloud by cloud all year round, but visitors to the Northwest Vietnam generally known under the name O Quy Ho Pass. O Quy Ho Pass have long winding stretch of road on Highway nghoeo 4D, in which 2/3 of the way located in Tam Duong district, Lai Chau, third left lying in the Sa Pa, Lao Cai. This is probably a record holder of the pass length in the mountains northwest Vietnam, with a length of nearly 50 km longer than the Pha Din Pass (32 km long, located at the boundary of Dien Bien and Son La Province) or Khau Pha Pass (near 40 km, the Yen Bai). The height, the length of the dangerous and cause O Quy Ho mountain pass known as unorthodox " King of Northwest Pass".
