President Tomas Guardia established the prison on San Lucas in 1873. In an irony that the island's history never quite escapes, Guardia abolished the death penalty a year later -- yet the prison he created became synonymous with cruelty. Prisoners' lives were short, and stories from the late nineteenth century described inmates being dropped into sewage pits, among other torments. The island's isolation in the Gulf of Nicoya made escape nearly impossible and oversight even harder. The prison operated for over a century, finally closing in 1991. Its buildings sat abandoned for a decade, deteriorating in the tropical humidity, before the island was designated a protected wildlife refuge in 2002. In August 2020, the Costa Rican legislature voted to elevate San Lucas to national park status -- the country's 30th.

The writer Jose Leon Sanchez spent nineteen years imprisoned on San Lucas. His best-selling novel, La Isla de los Hombres Solos -- The Island of Lonely Men -- drew from those years and brought the island's story to a national audience. Today, visitors can walk through the prison cells where decades-old graffiti still clings to the walls, a chapel that remains beautifully maintained and ready for Sunday mass, and a torture chamber that needs no interpretation. The former administrative buildings near the main dock have weathered into photogenic ruins. These structures are now classified as Patrimonio de Cultura -- cultural heritage sites -- protected by Costa Rican law.

What drew conservationists to San Lucas was its isolation -- the same quality that made it effective as a prison. Surrounded by the waters of the Gulf of Nicoya, the island's 468 hectares provided natural protection from mainland predators, allowing wildlife to flourish once human activity declined. More than 100 species of birds inhabit the island, including large numbers of waterbirds and flocks of wild turkeys moving through wooded and grassy areas. Howler monkeys, deer, and anteaters roam the interior. Crocodiles patrol the shoreline. Offshore, the waters hold hammerhead sharks, rays, sea turtles, and at least eight species of bats roost on the island itself. Indigenous groups lived here for centuries before Spanish colonization -- eight archaeological sites dating from roughly 1000 to 1500 AD have been identified.

San Lucas has nineteen small sandy beaches, though most of the shoreline is rocky, with sheer cliffs dropping to the water. A thirty-minute boat ride from Puntarenas -- typically costing eighty to one hundred dollars per person for a guided tour -- brings visitors to an island with no stores, no restaurants, and no lodging. Tour operators provide meals and drinks; independent visitors need to pack everything in and everything out. The experience is hiking, snorkeling, birdwatching, and walking through the ruins of a place that has been many things: indigenous settlement, colonial outpost, brutal prison, wildlife refuge, and now national park. The layers accumulate, each visible in its own way -- stone tools in the archaeological sites, iron bars in the cells, and the sound of monkeys where silence once meant something very different.