Kayan Mentarang National Park is located at Kalimantan Island and it is located at the border of Indonesia-Malaysia. The National Park consists of primary forest of 1,35 million hectares  with various kind of forest inside. It is the home of flora and fauna and many of them are not identified yet.

The National Park was once a Nature Reserve and then in 1996, it was appointed as Kayan Mentarang National Park. The National Park is the biggest primary forest in South East Asia. The name of Kayan Mentarang was derived from two major rivers stream to the national park, Kayan River which streams at the South and Mentarang River which streams at the North. Other source mentions that the National Park name derives from  Apau Kayan highland that stretchs from Long Kayan at the South through Apau Ping in the middle and Long Bawan at the North.

There are types of forest in Kayang Mentarang: Dipterokarp Forest, Fagaceae-Myrtaceae Forest, middle to high mountain forest and also heath forest or kerangas forest. There are also swamp forest, secondary forest, agathis forest, moss forest in the height of more than 1500 m.

Some flora diversity can be found here are: ironwood, pulai, ramin, jelutung, sugar palm, rengas, agathis, and gaharu. The national park is also home of various plants habitat such as pitcher plants, and orchids.

Kayan Mentarang is rich of wildlife. It is the habitat of more than 100 mammals and 15 of them are endemic animals. There are 28 primates species, and more than 300 birds species. Honey bear, banteng, clouded leopard, and white fronted surili.

BATU ULUI : is the peak of rock mountain located at Long Jelet hamlet, at the mouth of Jelet River and Pujungan River. From the peak travelers can see the  rainforest landscape. The hiking will start at Long Pujungan and then crusing aong river for about 4 hours and then trek for about 2 hours through slopy and slippery slope.

U’UNG MELU’UNG WATERFALL is located at Long Pujungan. It is a 50 meters high waterfall. It takes about 30 minutes walk from River Pujungan. There is a salty spring located nearby the waterfall where wildlife can be spotted, if you are lucky.

ROCK GRAVEYARD is one of interesting site can be explored in Kayan Mentarang National Park. It is located at the estuary of two rivers : Pujungan and Bahau River. The graveyard was the heritage of Ngorek tribe, and the region has not been inhabited for more than 400 years ago.

LONG TOA SAVANNAH is the habitat of wild banteng. In here, travelers can also see deers and pigs. The animals usually can be spotted morning and late afternoon. There is a humble lodge in this savannah.

DAYAK CULTURE AND TRADITION is one of the main interest of travelers visiting the National Park. In certain days they have dance performance and also traditional celebrations. When visitors come, they also perform rituals. There are sub ethnic of Dayak Tribe in the surrounding of Kayang Mentarang National Park, such as: Kenyah Tribe, Kauan Tribe, Lundayeh Tribe, Tagel, Saben and Puanan, Bakung, Badeng, Makulit and Makasan that spread in 50 villages in the region.

Kayan Mentarang National Park can be accessed by flying 1 hour from Samarinda to Tarakan and then you will cruise by speedboat through Mentarang River for 6 hours or more, and it is subject to weather and river water level. Rivers to access the national park are  Bahau river, Kayan River or Mentarang River.