The Lacandon Jungle is situated in north eastern Chiapas, centered on a series of canyonlike valleys called the Cañadas, between smaller mountain ridges oriented from northwest to southeast. The ecosystem covers an area of approximately extending from Chiapas into northern Guatemala and southern Yucatán Peninsula and into Belize. This area contains as much as 25% of Mexico's total species diversity, most of which has not been researched. It has a predominantly hot and humid climate (Am w" i g) with most rain falling from summer to part of fall, with an average of between 2300 and 2600 mm per year. There is a short dry season from March to May. The predominate wild vegetation is perennial high rainforest. The Lacandon comprises a biosphere reserve (Montes Azules); four natural protected areas (Bonampak, Yaxchilan, Chan Kin, and Lacantum); and the communal reserve (La Cojolita), which functions as a biological corridor with the area of Petén in Guatemala. Flowing within the Rainforest is the Usumacinta River, considered to be one of the largest rivers in Mexico and seventh largest in the world based on volume of water.