This 20km-long, sandy barrier island (in some places only 300m wide) has swimming holes and lots of wildlife, including hundreds of migrating bird species, crocodiles, nesting turtles and mosquitoes galore. On one side of the uninhabited island you’ll find long, wild, sandy beaches facing the Pacific, on the other, red and black mangroves reflected in emerald lagoons. Las Peñitas ranger station and various accommodations offer guided boat tours (US$55 for up to four people) and kayaking excursions (US$12 per person).

　　During the turtle egg-laying season, which runs July through January and peaks in September and October, thousands of olive ridleys, careys and leatherbacks lay their eggs in El Vivero, close to the Las Peñitas entrance. For the best wildlife-watching opportunities, it's best to go at low tide, or at dawn or sunset if you're especially interested in birds. If it's turtles you're here to see, try a nighttime turtle tour (US$25 per person, June to December) with guided camping.

　　You can also go to the reserve yourself if you can negotiate a ride with a local fisher. Another option is to hire a local guide (US$10) – ask at the Las Peñitas ranger station or stop into the hotel-restaurant-tour outfitter Barca de Oro.