The park now includes over 19,000 hectares (46,900 acres) and protects 22 miles of nesting beach from the mouth of the Tortuguero River south to Parisimina. The park, and the Barra del Colorado Wildlife Refuge to the north, comprise the largest remaining adjoining tract of lowland wet tropical forest on Costa Rica's Atlantic Coast.

Tortuguero beach is the most important nesting site of the endangered green turtle in the Western Hemishpere. Giant leatherback, hawksbill, and loggerhead turtles also nest here.

The green turtle population is believed to have come perilously close to extinction in the 1960s when nearly every female turtle arriving to nest in Tortuguero was taken for the export market for turtle soup.