Caño Island Biological Reserve

The boat anchors in blue water above a reef you can already see from the surface. Below, white-tip sharks trace slow arcs over coral while schools of jack shift direction in unison like a single silver organism. On the island above the waterline, pre-Columbian stone spheres sit in the jungle understorey — burial offerings from a civilisation that vanished, placed on an island where no one ever permanently lived.

Caño Island Biological Reserve lies twenty kilometres off the Osa Peninsula in Costa Rica's South Pacific. Its reef system covers five square kilometres with sixteen coral species and over 150 fish species, and visibility typically reaches twenty metres. Reef white-tip sharks, silvertip sharks, and occasional nurse sharks circle the submerged pinnacles year-round. The island's forest interior holds stone spheres identical to the Diquís spheres on the mainland — UNESCO World Heritage objects whose purpose and production method remain debated. Protected since 1978, the reserve has been without permanent human presence for over four decades, leaving its reef and forest in a state rarely found this close to a continental coastline.