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The Precambrian basement of Mananara, dating back 2,750 million years, belongs to the Antongilian system. Following geological metamorphisms that led to this substrate of rocks composed of amphibolites, micaschists, greenschist and schist, granitic intrusions of about 770 million years ago appeared which, together with Neocene alteration and erosion, are responsible for the orthogonal shape of the region's relief with narrowly linear valleys, rock walls, cascades and waterfalls, falling rocky shores and the hydrographic network following the lines of the landscape and valleys. This explains the difficulty of access to monitor the park, the history of linear fragmentation of the forest and the human occupation along the lines of valleys. The density of vegetation and the ability of forest regeneration worsen the problems as they favour the camouflage of offenders.
Due to presence of the South Equatorial Current coming from South Asia that runs along the east coast to become Madagascar's southward current, this current brings warm surface waters in all seasons and conditions the water temperature to never drop below 18°-20°C. In order to develop, coral reefs require warm, clear water (above 18°C) on a shallow bottom with 30 to 35% salinity, which is the case for the Mananara Nord Marine Park. At the highest sea (during high tide minus the half maximum hight of a wave) the water is between 25m and 35m deep. The Malagasy east coast is swept throughout the year by the Alizé(trade wind). The average wind speed is 20m/s. The Mananara Nord National Park consists of a land and marine park that are both rich in biodiversity as well as natural and original beauty.The marine park is the first created in Madagascar. The site is commonly called Nosy Antafana. It is a set of three islets located 2.5km off [[Sahasoa]]. The largest is Nosy Be or [[Nosy Antafana]], where a fresh water source is located. The second is [[Nosy Rangontsy]], named after the man whose remains were the first to be deposited there. On this islet is a mangrove swamp, an expanse of brackish water with fish and in the east huge masses of granite. The last island and the smallest is [[Nosy Hely]]. It is a real marine ecosystem with various representative ecological niches. Coral reefs are among the most beautiful and rich in biodiversity of the east coast of Madagascar. The land park represents the eastern eco-region with littoral forests and forest islands.
