La Encrucijada Biosphere Reserve (Spanish: Reserva de la Biosfera La Encrucijada) (established 2006) is a UNESCO Biosphere Reserve situated in the Pacific Coastal Lowlands physiographic region of Mexico. It covers 144,848 hectares (559.26 sq mi) stretching over six municipalities in the Costa de Chiapas (Pijijiapan, Mapastepec, Acapetahua, Villa Comaltitlan, Huixtla and Mazatán). It is composed of two large coastal lagoon systems that correspond to two core areas (La Encricijada and Palmarcito), and a wide variety of natural ecosystems including mangroves, zapotonales, tule swamps and marshes, as well as patches of tropical seasonal forest, coastal dunes and palm trees.