Batang Ai National Park

Batang Ai National Park is the only place in Sarawak where you can see wild orangutans and, due to being so remote, is one of the least known places to visit.
With the highest orangutan population density in central Borneo, it's estimated there are around 1,000 individuals, the chances of seeing a wild orangutan are good. You can also see gibbons, langurs and hornbills and meet the indigenous Iban community, who are involved in park conservation and management and are masters of the longboat and orangutan tracking.
The only way of getting to the orangutan zone in Batang Ai is on a multi-day tour, which usually includes travelling upriver on a longboat, staying in jungle camps or Iban longhouses, and treking into the dense jungle. It'll be hot, humid, slippery and you might encounter your fair share of leeches, but seeing orangutans swinging around their natural habitat will be worth it.