Rio San Juan forms the border with Nicaragua. Between it and Laguna de Tortuguero lie 91,200 hectare of swampland and rain forest teeming with exotic wildlife. The labyrinthine lagoons and rivers boil with tarpon, snook, and antediluvian garfish, making the refuge the premier sport-fishing centre in Costa Rica. Endless green rain forests are fills the horizon; the forests are gnawed at by loggers, and banana plantations push up against the park’s southern borders.

Swampy sloughs meander from lagoon to lagoon. Most backwaters are inaccessible; here manatees breed in relative isolation. All along the riverbanks are dilapidated shacks on stilts. The river is entirely within Nicaraguan territory; you will need a passport and be prepared to pay a fee.