As you head northwest along the Caribbean coast past the beaches of Playa Blanca, the last stop along the Guatemalan Caribbean shores is the Río Sarstún, which, despite the Guatemala-Belize Border Dispute, forms the current border between Belize and Guatemala.

This beautiful jungle river has just recently become a viable option for exploration now that it is fully protected as a park administered by conservation group FUNDAECO (www.fundaeco.org.gt). The park ($20 admission) protects 2,000 hectares of tropical rainforest, flooded forest, wetlands, and mangroves.

You can kayak and explore wetland canals, see the recently discovered Cerro Sarstún cenote, swim in the emerald-green waters of a small lagoon, or hike along well-maintained nature trails, all of which are included in the price of admission.

Accommodations are in the Eco-Albergue Lagunita Creek (tel. 2253-4991 and 5241-9342, www.fundaeco.org.gt), a modern facility with clean, shared-bath dormitories with bunk beds for $7 and rooms with private bath, queen-size bed, and balcony overlooking the river for $30 d. You can buy meals from the local community for $3–5.

There’s also a biological station here. Contact the lodge or FUNDAECO prior to your visit to arrange transportation. You can also hire a boatman to bring you from Lívingston, which will cost about $200 for a day trip.