Dry season is the best time to see monkeys and other animals on shore. Diving can be good year-round, though visibility can vary dramatically day to day.
The waters off Bahía Damas, a bay on the east side of the island, have the largest coral reef in Central America (135 hectares) and the second-largest in the eastern Pacific. That and the density and diversity of large sea creatures have made Parque Nacional Coiba  famous among scuba divers.
The sea life in some spots is what a nature guide friend calls “aggressive—everyone in town comes by,” including turtles, orcas, and sharks that zip right past divers.
Because of the fragility of the environment here, and the necessity of knowing these waters well, diving trips should be arranged through reputable professionals. As my friend put it, anyone found tossing an anchor onto the reef will likely get an anchor tossed at his head.
A good and accessible spot for snorkeling is Granito de Oro, a lovely islet a short boat ride from the ANAM field station . There are coral fields, including brain and fan coral, and schools of pretty little tropical fish just off the islet’s sandy beach. The current becomes very strong just beyond the rocky cove—even strong swimmers should be careful not to swim out too far.
There are two trails—short walks, really—around the ANAM ranger station. The Sendero del Observatorio (Observatory Trail) is a 15-minute walk at a very slow pace that leads to an elevated bird-watching station. It’s not a particularly good place to watch birds, but the view is nice.
The trail starts behind cabin 6. Note the sign that says the trail is “approximately” 527.81 meters long. Another brief walk behind the kitchen leads up to a second lookout point on a small hill. It has a lovely view of the sea and Isla Coibita.
The Sendero de Los Monos (Monkey Trail) is not accessible from the ranger station. It requires a boat ride to the area near the Granito de Oro islet. It takes about an hour to walk and curves inland from one beach to another. There are howlers and white-faced capuchins along the trail, but you’d be lucky to spot them; best bet is in the dry season.
Other flora and fauna found along the trail include fiddler and hermit crabs, coconut trees, the guinea pig–like ñeque de Coiba (Dasyprocta coibae), boa constrictors, and fer-de-lance snakes.
Sportfishing within Parque Nacional Coiba  limits is catch-and-release only and requires a permit, and the government has finally begun to enforce this law. Hannibal Bank, between Isla de Coiba and Isla Montuosa, is an especially famous fishing spot.