There are two destinations in Kalimantan and Brunei you should check out if you plan to spend a nice day among pure nature and take a walk with birds flying around.
In East Kalimantan, there is Bukit Bangkirai Park, famous for huge trees, hornbills, and its canopy walk. The latter hangs at the height of 30 metres and consists of five suspension bridges. When you walk along the tree tops, it sways, swings, and shakes because it is made of ropes, nylon netting, steel cables, and wooden planks. You also have to climb wooden stairs up to reach it.
When in Brunei, there is only one treetop walk located within the Ulu Temburong National Park. This place is remarkable due to the virginity of its nature, as only about 1% of an area is accessible for tourists. You have to climb wooden stairs up to the top of the tower where a canopy walk starts. Its highest point is 60 metres above the ground, so you can actually feel yourself on top of the whole park.
The best time of the year to visit these places is between May and September when there is less chance of rain and the wooden stairs won't become wet and slippery. It is also recommended to go there in the morning when a mist falls down on the trees and early birds greet each other and the new day.