Mountain gorilla trekking takes place throughout the year but the best time to go for the mountain gorilla trekking is during the drier months of June, July, August, early September and from December to February. Trekking mountain gorilla in the drier months is less difficult and more enjoyable as there is less or no rainfall and trails followed while tracking are dry, mud-free and not slippery. Gorilla trekking permits cost US$ 1500 in Rwanda, US$ 700 in Uganda.