Cuc Phuong is Vietnam's oldest national park, established in 1962 and covering 222 square kilometres of primary tropical forest about 120 km south of Hanoi. The park shelters an extraordinary diversity of plant and animal life, including several species found nowhere else — among them the Delacour's langur, one of the rarest primates on earth.
The Endangered Primate Rescue Center, based within the park, breeds langurs, gibbons, and lorises for eventual release and is well worth a visit. A network of trails leads through dense forest to a thousand-year-old tree, ancient caves with traces of prehistoric human habitation, and viewpoints over the limestone karst landscape. The best time to visit is between December and April, when the weather is dry and butterflies fill the forest clearings by the thousands. Simple guesthouse accommodation is available inside the park.