Isla Gorgona, a wildlife-filled national park where humpback whales gather to mate, was once an inescapable jungle prison for Colombia’s most violent criminals.

Our boat departed on a cloudy morning, shortly after sunrise. We were 45km from mainland Colombia when the first humpback whale breached the surface, exposing its massive white underside before splashing back down with an impressive display of power and grace.

Behind us, the sun showed itself for the first time, but an ominous cloud still hovered above the island in the distance. Clouds always seemed to loom overhead, our driver explained, and I imagine that the darkened skies served as the final harbinger of doom for the condemned souls sent to Isla Gorgona’s inescapable jungle prison between 1959 and 1982, before the government closed it and turned it into a national park in 1985.

Dozens of fresh water streams spread across Gorgona like arteries, the lifeblood of an island teeming with flora and fauna. Stand somewhere for a few minutes and it is difficult to avoid seeing something move. Crabs sprint across the beach before crawling back into small holes in the sand. Lizards drop down from trees. Sloths lumber in the branches high above. Eagle rays, turtles and reef sharks whirl around in the sapphire sea.

But before it was a wildlife mecca, this 24sqkm volcanic island served as a formidable fortress that housed Colombia’s most violent criminals, with stone walls, barbed wire and prison guards acting as only the first line of defence. The 56km of rough, shark-infested waters and the venomous snakes for which the island is named usually put an end to any hope of escape.

Like the gorgons – the demons in Greek mythology whose hair of venomous snakes turned witnesses to stone – the serpents that slither on land and sea can be deadly (it is still forbidden to go anywhere on the island alone or after dark, and visitors are given gumboots to walk around). Still, the conditions in this zoo, where the humans were caged and the animals ran wild, were so miserable that there are stories of desperate prisoners seeking poisonous bites just to receive some tender nurse care and a short reprieve from the overcrowded cells and torture chambers.

The nurses, along with scuba divers who long ago discovered the island’s world-class marine life, helped transform the penal colony into a national park by spreading word of its atrocious conditions.

Only 30 years after the prison’s closing in 1982, verdant foliage twists itself around the crumbling ruins that have become one with the jungle. And since becoming a national park in 1985, wildlife enthusiasts have enjoyed greater access to the 147 species of birds, 100–plus species of insects and hundreds of species of terrestrial and marine fauna and flora.  

The terrestrial wildlife, like monkeys, caimans and the blue anole (the world’s only pure blue lizard, endemic to the island), is staggering. But the marine life has been attracting divers since the days when prisoners were still locked away.

Every year in June or July, a few visitors are lucky enough to witness the spectacle of more than 1,000 humpbacks arriving in Gorgona’s tropical waters, where they stay through October for mating and calving. With the massive whales come other giants of the sea, like whale sharks and sperm whales and occasionally hammerheads, sea lions and dolphins. There is no question whether visitors during this time will see the humpbacks. The question is usually, how many?

In addition to their show of splashing around the surface of the water, the humpbacks enchant visitors as their cries echo below the water, conducting a beautiful symphony for divers used to listening to just the sound of their own breathing.

Gorgona’s remote location 56km off the coast of Colombia has helped keep its ecosystem healthy, but it also means the island can be inconvenient to reach. It is a 12-hour boat ride from Buenaventura, a coastal city of more than 300,000 people about 10 hours from Bogota or four hours from Cali, or an hour-and-40-minute boat ride from Guapi, an Afro-pacific town near the border of Ecuador. No roads lead to Guapi, but its one-runway Juan Casino Solis airport services flights to-and-from the southern cities of Cali and Popyan. The daily can flights fill up fast, so book ahead of time.

"Welcome to Colombia; welcome to my country", the island's head of tourism said when I arrived. "And welcome to Gorgona; this place belongs to everyone." 

Unfortunately, a trip to Gorgona comes with a hefty price tag, making a visit an unattainable dream for many Colombians, especially the poverty-stricken residents of Guapi, to whom the island politically belongs.

Until recently, visitors could make day trips to Gorgona from Guapi or spend a night there for as little as $12. But the government’s 2009 decision to give a private company sole control over all tourism on the island has meant exponential price hikes. A park permit, night in a basic bungalow in the remodelled prison-guard quarters, three meals and a return boat ride from Guapi costs about 460,000 Colombian pesos, and additional nights are 250,000 pesos. All activities — whale watching, snorkelling, even walking around the island — are extra. Book through the sole tourism company that services the island, Aviatur.

The only benefit of a difficult, costly visit is that relatively few people ever make it to Gorgona, which helps maintain its flourishing ecosystem and leaves you blissfully alone in incredibly wild surroundings.

Leaving the island, torrential rain battered the boat and the rough sea had no desire to give us a smooth journey back to Guapi, typical for this perpetually hot, wet climate. I saw no sign of life — no whales, no monkeys no lizards or snakes. But they were surely there, hiding from the storm. This island, after all, belongs to them.