Pantanos de Centla

Frontera sits at the edge of the Pantanos de Centla, the delta where Mexico's two biggest rivers, the Grijalva and the Usumacinta, spread out into a maze of channels, lagoons, marshes and mangroves before reaching the Gulf. The reserve covers about 302,700 hectares, mostly in Tabasco with a small part in Campeche, and is often described as the largest wetland in North America. It was declared a biosphere reserve in 1992 and is also a Ramsar wetland and part of UNESCO's network of biosphere reserves.

The easiest way in is the Uyotot-Ja' interpretation center, whose Chontal Maya name means "house of water." It has exhibition rooms about the wetland and the people who live from it, and a 20-meter tower that looks over Tres Brazos, the spot where the Grijalva, the Usumacinta and the San Pedrito join.

From the dock, local community cooperatives run boat trips into narrow channels lined with mangroves and water lilies. Birds are the stars: more than 200 species have been recorded, including herons, egrets and the huge jabiru stork. With luck you may also see crocodiles, iguanas, turtles and howler monkeys; manatees live here too but are rarely seen.