Ratanakiri is after Mondulkiri one of the most popular regions for trekking and exploring the Cambodian forests. To reach them, you have to take the main road, sometimes called "death road" or "Highway of death" during the rainy season. Indeed, it is mainly composed of a thick layer of gravel and dust which can be slippery. During the dry season, it is practicable at low speed. There is very little traffic, and you will cross natural reserves, in particular that of Lumphat. You can set aside a day or two to explore the northern jungle of Ratanakiri.