The Hoang Lien Mountains lie at the south-eastern extent of the Himalayan chain. The national park is located on the north-east flank of these mountains and includes Vietnam's highest peak, Fansipan, at 3,143 m (see map). The lowest point is 380 m but most of the national park lies above 1,000 m. The flanks of the mountains are very steep and many areas are almost inaccessible on foot. Between Fansipan Mountain and Sa Pa town, lies the Muong Hoa valley, which has been terraced for wet rice agriculture. This valley becomes wider towards the east of the national park.