Tree House Hostel in Sigiriya is a hostel nestled in the jungle. You sleep in actual treehouses with beautiful views of the surrounding nature and wildlife. The staff put together some activities for everyone to join in on like sunset hikes and lake days. Breakfast is included and changes everyday.
Fair warning, if you don't like bugs/spiders/mosquitos then maybe stay elsewhere. There is no AC and you sleep in a mosquito net. Its a bit rough but a unique experience nonetheless. Some people loved it but I personally missed having a nicer room with windows that closed out the bugs.