The far north of the Zona Norte is an isolated region, culturally as well as geographically, closer in spirit to Nicaragua than to the rest of the country and mostly devoted to sugar cane, oranges and cattle. Years of conflict during the Nicaraguan civil war made the region more familiar with CIA men and arms-runners than with tourists, but it’s all quiet now.

Most visitors are here to see the Refugio Nacional de Vida Silvestre Caño Negro, a vast wetland that makes up one of the most remote wildlife refuges in the country. Located at a key point on the migratory route between North and South America, it acts as the resting place for hundreds of migrant bird species and is considered by the Ramsar Convention on Wetlands to be the third most important wetland reserve in the world.

Caño Negro is accessed from Los Chiles, near the Nicaraguan border, and the only village of any size in the far north. The drive up here, along an unnervingly straight stretch of road from San Carlos, takes you through a flat landscape of rust-red soil and open pasture, broken only by roadside shacks, with the Llanura de Guatusos stretching hot and interminably to the west. During the Nicaraguan civil war, Los Chiles was a Contra supply line. Nowadays, there’s a climate of international cooperation, helped by the fact that many of the residents are of Nicaraguan extraction, and crossing the border is straightforward, as long as your documents are in order. Incidentally, the Río San Juan is technically Nicaraguan territory – the border is on the Costa Rican bank – though Costa Rica is allowed free use of the river.