The beach hamlet of Mazanillo, actually located within the park, is home to some of the finest white-sand beaches that the Caribbean side has to offer. From the town, several trails make their way up to Mona Point 6 miles (10 km) away, beyond which lies the only red mangrove swamp on Costa Rica's Atlantic coast. Equally rare are the two palm swamps found inside the park that protect tapirs within the stagnant forest.

The tropical vegetation and remote location draw a plethora of tropical birds to the park-more than 360 species-including the elusive harpy eagle. This large population certainly makes for good birding.

Marine turtles-leatherback, hawksbill, and green sea-frequently nest on the park's southern beaches. Although not a primary nesting site for turtles mainly due to human activity, conservation efforts have been stepped up in recent years by community members to try to increase the local populations.

Much of the KeKöLdi Indian Reserve spills into Gandoca-Manzanillo to safeguard indigenous Bribri and Cabecar tribal land. Indigenous tribes inhabit sections of the park, subsisting off the forest and experimenting with ecotourism.

A wide variety of fauna inhabits the park such as manatees, dolphins, Venus sea fans, and eagles. Snorkeling and scuba diving offers intimate views of tropical fish that weave in and out of the living coral.

The best time to visit Gandoca-Manzanillo is during the dry season, March through April and from September to October, as the park receives plenty of rainfall. Both Manzanillo and Gandoca provide access to the park. Accommodations at these hamlets are sparse. Nearby Puerto Viejo is the best option for those looking to spend at least a few days in the region.