Kalimantan is the Indonesian portion of Borneo and is very famous for its tropical rainforests which are even older than the Amazonian ones and where you will find many unique and almost extinct animal species like the Bornean orangutans.
The best way to enjoy Kalimantan would be by river cruises along meandering jungle lined rivers, passing islands with orangutans visible in the trees and the splashes of kites, hornbills and kingfishers overhead. Further upstream you can visit villages and meet the inhabitants still dependent on the jungle and from the river for their livelihoods.
vKalimantan is also renowned for many diving activities that take place in the Berau Archipelago in the Celebes sea, around the islands of Derawan, Sangaliki and Manatua in East Kalimantan. Tthere are also some less visited dive sites in West Kalimantan, these include Batu Payung and Radayan island in the vicinity of Singkawang and the Karimata islands reserve further south off the coast from Ketapang.