With an area of 152 000 ha, the Park includes a part of the huge mountain of the Bemaraha, and it is, by its size the second Protected Natural Area of Madagascar. It spreads over near 90 km of long and 10 to 20 km of width all along the West facade of the Island in the province of Majunga. It is a karstic formation , delimited to the east by 400 m high abrupt cliffs over the valley of the river Manambolo and westward by gentler slopes. Southward the reserves a formation of pinnacles which access is extremely difficult looks like a lunar landscape .
The reserve is situated in the heart of a dry forest, in the mountain of the Bemaraha essentially constituted of calcareous Karst or « Tsingy » with very indented relief. The mountain contains many caves and resurgences.
Waterway coming from the plateau are seasonal or permanent.

Rains are seasonal from November to April and the dry season lasts 6 to 8 month. The average annual temperature is superior to 26°C.

The deciduous forests of the reseve represent the families of Flacourtiaceae, Euphorbiaceae, Annonacceae, Bonbacaceae and Moraceae. The reserve has several species of Delonis and the only wild banana trees of Madagascar: Musa perrieri-Musaceae. In rocky areas, species of aloes are common, and a part of the reserve is covered of anthropogenic savannah .

A rare chameleon with few specimens known , the Brookesia perarmata, lives in the reserve. Among the 53 counted bird species, the gray front water rail Canirallus kioloides has been discovered in 1987 in the reserve that constitutes the unique dry forest known frequented by this specie . There are 11 species of lemurs, among them the Propithecus verreauxi deckeni. Furthermore, the reserve is the unique protected area where can be found the endemic rodent Nesomys rufus lambertoni. This rodent is so much particular that it deserves the status of specie .