The 22,000-hectare Reserva Forestal del Humedad Internacional Terraba-Sierpe is a vast network of mangrove swamps fed by the waters of the Ríos Terraba (to the north) and Sierpe (to the south), which near the sea form an intricate lacework of channels and tidal esteros (estuaries) punctuated by islets anchored by manglares (mangroves).

The delta, which extends along 40 kilometers of shoreline, is home to crocodiles, caimans, and myriad birds.

You can hire dugouts and motorboats for guided tours from Sierpe, Palmar, or Cortés ($125 full day, up to six people).