The Caño Island Biological Reserve lies 20 kilometers off the Osa Peninsula, where five ocean currents converge to create Costa Rica's most biodiverse marine corridor.
The island's waters shelter 15 species of hard coral and more than 200 fish species, including white-tip reef sharks, spotted eagle rays, and seasonal humpback whales. UNESCO designated the surrounding Osa region a World Heritage site in 2020, recognizing the ecosystem that stretches from cloud forest to deep-water trench without interruption.
Archaeological surveys conducted between 1998 and 2004 uncovered 23 pre-Columbian burial sites on the island, some dating to 300 BCE. The stone spheres found here—ranging from 10 centimeters to two meters in diameter—match those at Diquís Delta sites 50 kilometers inland, suggesting the island served as a ceremonial waypoint for ancient maritime traders. Costa Rica's National System of Conservation Areas restricted public access to these terrestrial zones in 2012, channeling all visitor activity to designated snorkeling sites along the northwest and southern coasts.
The reserve's most frequented dive sites—Paraíso, Cueva del Tiburón, and Bajo del Diablo—descend from shallow coral gardens at three meters to vertical walls plunging past 30 meters. Visibility averages 18 to 25 meters year-round, peaking during the December-to-April dry season when plankton blooms subside. Morning departures from Uvita, Sierpe, and Drake Bay take 45 to 90 minutes depending on sea state, with most operators anchoring by 09:30 to coincide with peak fish activity. The 15-dollar-per-person conservation fee, introduced in 2018, funds reef monitoring and patrol operations across the reserve's 5,800 hectares of protected ocean.
Snorkeling costa rica cano island tours include gear, bilingual naturalist guides, and lunch served on board or at Playa San Josecito, the island's only permitted landing zone. Operators limit group sizes to 12 snorkelers per guide to minimize reef contact, and seasonal closures between September and November protect nesting olive ridley turtles along adjacent mainland beaches.
6 hr
