Pu Mat National Park and the Pu Huong and Pu Hoat nature reserves are the core zones of the UNESCO-recognized Western Nghe An Biosphere Reserve, at 1.3 million hectares the largest such reserve in Southeast Asia.
The park, whose name means high slope in the language of the Thai tribe, is located in the southwest of Nghe An Province along the border with Laos and extends from the crest of the Truong Son Range down the steep eastern flank to the evergreen lowlands.
Spread over Anh Son, Con Cuong and Tuong Duong districts, it comprises a protected core zone of 95,000 hectares and a buffer zone of 86,000 hectares.
Pu Mat boasts amazing biodiversity in its moist forests. Surveys in recent years by the EU-funded Social Forestry and Nature Conservation in Nghe An Province have turned up close to 2,500 plant species, three of them new to science, and 1,000 animal species.
Several critically endangered species are found there, including one of the world's rarest mammals - the Saola, also known as the Vu Quang ox or Asian unicorn (Pseudoryx nghetinhensis).
This bovine denizen of the Truong Son's remote, steep-sided valleys first came to the attention of the scientific community in 1992, though the local tribes had been hunting it for centuries.
Including the Saola, surveys and research have confirmed the presence in Pu Mat of five mammals endemic to Indochina, the other four being the northern white-cheeked gibbon, red-shanked douc, Truong Son muntjac and Annamite striped rabbit.
Other globally threatened mammals that live in the national park include the dhole, Assamese macaque, Indochinese tiger and Asian elephant.
Pu Mat's managers say the wide and scattered variety of plants and animals makes conservation very hard. There's too much to do.
They have spent much time in the forest gathering information about the species living there, and then mapping their habitats to form a basis for reliable evaluation and effective conservation.
As part of the research and conservation efforts, the Wild Animal Rescue Center in Pu Mat National Park raises and takes care of different species like squirrels, tortoises and bears.
Animals are brought to the center from around the country. Most of the new arrivals are very young, are in critical health, or have been wounded by poachers. The center nurses the animals until they are fit for release back into the wild.
One of the inmates is a Tibetan bear that weighed less than two kilograms and was in poor condition when it was taken to the center in 2008. Now, it weighs more than 70kg and is strong enough to survive in the rugged mountains of Nghe An.
The park's managers say Pu Mat would be an ideal place of conservation for the whole of Indochina for different species in danger of extinction.
The jagged and forested landscape, whose highest point is the summit of Mount Pu Mat at 1,841 meters above sea level, is breathtaking.
In addition to the peaks of the Truong Son Range, the notable scenery includes the beautiful Giang River, the crystal clear Moc Spring, and the impressive Kem Falls, where enormous volumes of water plummet 150 meters year-round and cool a wide area with their spray.
Visitors can take a boat ride up the Giang River, or walk under the big shady trees of the forest full of birdsong and dappled sunlight at sunrise or sunset.
Bat-filled labyrinths of karst cave are another feature. The local villagers, who have been known to take visitors on guided tours of the caves, say some of them extend for more than ten kilometers.
Members of the Thai tribe make up the vast majority of the local human population. They live in villages, grow rice and vegetables, raise cattle and poultry, and make bamboo products. More famously, they manufacture a traditional floral brocade that is known throughout Vietnam and farther afield.
Other residents of Pu Mat include the Kinh, the majority race of Vietnam, and the Dan Lai, who live mostly in the villages of Co Phat and Ban Bung in Mon Son Commune in the southeast of the park.
Tourists can visit their villages, observe their different customs and way of life, taste the alcoholic brew called rượu cần, and even join in the bamboo stick dance and other social activities.
To make it more interesting for visitors, Pu Mat has built a traditional Thai trading village where they can get to know more about the lives of the tribal people in the national park.
Covering 1,303,285 hectares, Western Nghe An Biosphere Reserve is the largest World Biosphere Reserve in Southeast Asia and was formally recognized by UNESCO in September 2007.
It is one of the eight World Biosphere Reserves in Vietnam. The others are Can Gio Mangroves Forest; Cat Tien National Park, Cat Ba Archipelago, Hong (Red) River Delta, Kien Giang Coast and Island Area, Ca Mau Tip; and Cu Lao Cham (Cham Island).