[3] The park is bounded on the south by the Sarstoon River, which forms the border with Guatemala.

Wetland habitats include 1,100 hectares of freshwater sphagnum moss bog, which are distinct in the region, and the Belize's only stands of comfra palm (Manicaria saccifera).

The park also includes a brackish-to-saline inland lagoon, which forms a transition between the freshwater wetlands and 9,600 hectares of saline mangrove swamps.

[2] The park is home to several threatened and vulnerable species of animals, including the black howler monkey (Alouatta caraya), hickatee turtle (Dermatemys mawii), Baird's tapir (Tapirus bairdii), West Indian manatee (Trichechus manatus), and Morelet's crocodile (Crocodylus moreletii).

[2] Threats to the park include illegal logging of valuable mahogany, cedar, and rosewood timber.