Crystal Mountains national park (Monts de cristal)
This national park, is actually 2 areas as you can see from the map to the right (The twin parks Mbe National Park and Mt Sene National Park ).
They are split by some unprotected land in between, though at the current time, this land is still forested and pretty wild. They are known for having an incredibly high plant diversity.
Apart from forest elephants and a number of monkey species ( including black colobus monkey), forest buffalo, Ogooué talapoin monkey, Mandrill, chimpanzees, the white-collared mangabey, the hippopotamus, forest elephants, leopard, giant pangolin, the water chevrotain, six species of duiker and western lowland gorillas. There is 48 species of reptiles that are found in the reserve, but it is thought that the total would be closer to 65 (this includes the forest crocodile, the false gavial, the forest tortoise, the ornate monitor and the African python), and 340 species of birds. There are also many different species of butterfly. Even a species, known more widely, as a Savannah species such as the aardvark are also found here.
This is a fully intact ecosystem, and a fantastic part of Gabon to visit. What is more, it is only 2-3 hours drive from Libreville.
Below is a French video showing some of what the national park has to offer in terms of accomodation.