he Zahamena National Park, created in 1997, is located on the eastern part of the island, 70km northwest of Tamatave and about 25 km east from Lake Alaotra. The protected area has a total surface of 643 km², from which 423 belong to the National Park, and the rest is catalogued as Integral Natural Reserve and therefore not opened to visitors. Although the isolated location of this area has helped to its conservation, the actual human pressure of the Sihanaka and Betsimisaraka populations constitutes the main threat to Zahamena. The climate is humid, with moderate temperatures and showers all year around.
The park is divided into two areas (the western and the eastern one), which are partially separated by a corridor that includes several villages. It is still a very little known area, and naturalists are currently carrying out surveys to improve the scientific knowledge of the biodiversity found here.
The landscape is very hilly, with several steep-sided valleys drained by rivers, some of them flowing into Lake Alaotra. At lower altitudes the thick humid evergreen forest has a 15-20 m high canopy. The medium levels are dominated by bushes and secondary forests covered with tree-ferns and screw-pines called Pandanus. On the highest areas we find humid forest passing onto a dense montane forest.