Inside Panama's brutal haunted prison island that became a tropical paradise

The jungle rustles with macaws and the songs of white-throated thrushes as the Pacific Ocean throbs against the coastline. Under an almost trite blue sky, Coiba Island, with its towering palm trees and untouched beaches looks every bit a paradisiacal holiday destination.

Throw in a few overwater villas and it wouldn't look out of place in the Maldives. But lurking beneath this postcard-perfect facade is a dark history, and one that visitors to the island might end up experiencing a little more of than they’d like.

As recently as two decades ago, Coiba was the world’s largest island prison. Spanning about 500 square kilometres and located off the Pacific Coast in the Panamanian province of Veraguas, Coiba is also the largest island in Central America – perhaps one of the reasons it was earmarked as an early 20th-century penal colony. From 1919 until 2004, Coiba Island was home to murderers, rapists, drug dealers and a whole menu of shady characters who were sent to live and work here as prisoners. At its peak, the tropical island had 1,300 inmates, including many political prisoners, who were held in secret under the dictatorships of Panama's Omar Torrijos and Manuel Noriega.

Having disconnected from the mainland about 12,000 years ago due to rising sea levels, Coiba is difficult to reach, and even more difficult to escape from. “Some people might have tried to escape, but no one ever made it,” says Angelo Solanilla, co-owner of Balaena Travel and founder of Pacific Adventure Tours, who is guiding the group I'm travelling with through Panama's wild coast.

Once sent to Coiba, prisoners were only locked up for a few weeks until they understood the law of the land. With nowhere to go, inmates were then left to fend for themselves and it was the prison guards instead who would lock themselves in at night – likely fearful that inmates would take revenge for the harsh treatment they’d bestowed upon them during the day.

Unmarked graves and unidentified prisoners

“When people were sent to Coiba, they were forgotten about,” says Adiel Madrid, a member of Panama’s Aeronaval force, which now patrols the island. He takes us towards a clearing in the jungle where dozens of small stone crosses protrude from the ground. These weather-beaten markers are the only recognition of the hundreds of men for whom Coiba was the last stop on Earth.

Since Coiba closed as a prison, many dark tales of beatings, murders, abuse and torture have emerged from the island, at the hands of the guards, the prisoners and even the island's stray dogs.

Sporting camo gear and a cap to protect him from the hot Panamanian sun, Madrid takes us to see one of the prison units on the island. It was six to a cell, each encased behind rusted bars. Now it's entirely abandoned, with moss growing on the crumbling ground and on some of the hard sleeping stones.

We cross to another unit, closer to the beach and outside which is a stone sign that reads “Coiba Penal Colony. Under the administration of Dr Belisario Porras. November 1919”. That was the date when the thrice-elected Panamanian president converted Coiba into a penal island. There’s graffiti sprawled across what’s left of one of the walls.

My Spanish is poor, but I can make out the word merced – mercy.

Now that its uninhabited, other than official researchers, only the military is permitted to spend the night on the island. But according to Madrid, they're not here alone. Many servicemen have reported hearing odd noises after dark, including the rattling of bars coming from the prison cells and strange flickering lights in the dormitory-style lodge that the guards sleep and eat in.

“See the beds here,” says Madrid, gesturing towards what's left of some of the prison cells. “Last week, some of the guards here were laughing about something on patrol, and then all of the beds started to shake.”

When I ask whether he doesn't feel scared working here, “Si” comes the reply, matter of factly. “I've only heard noises, but last month, one of the guys I was working night shift with told me that he was on patrol and looked around and there was a very tall dark-haired man standing behind him, looking as if he were about to pounce. He moved away and turned around, and he was still there – following him. He moved again and then saw nothing. He was gone.”

From prison to Unesco-recognised paradise

But for all its dark past, Coiba has emerged victorious. A huge swathe of virgin tropical forest covers more than 80 per cent of the island. Its location – removed from the mainland – and its history as a prison has kept visitors away, inadvertently protecting its natural resources and leading it to bloom into the largest undisturbed jungle in Central America.

In 1995, while it still housed prisoners, it was declared a national park. After the last inmates were relocated in 2004, the entire Coiba archipelago in the Gulf of Chiriqui was designated a Unesco World Heritage Site. It’s now only reachable to visitors with a permit – who can access the island by boat from several points, including popular surfing haven Santa Catalina, or via plane – which is how we got there.

Chartering a small plane from Panama City, we landed on the island on to a grass-covered runway, the first time I've ever landed on anything other than tarmac or water. Bumping to a halt in the clearing, we first had to wait for our military escort to arrive and check our papers. Taking his duty seriously, he ended up staying to help one of my friends transport her not-so-small suitcase across the island's wild terrain.

In-the-know visitors head to the island for its untouched beaches, gushing waterfalls and natural hot springs, not to mention Coiba's surrounding waters. Encircled by a ring one of the largest protective coral reefs in the eastern Pacific Ocean, the sea here is a literal treasure chest of marine life. And the predator-free island has led to some remarkable developments in nature. Only a few years ago, researchers working on Coiba kept discovering piles of flat stones, balanced on top of one another and sometimes surrounded by pieces of coconut or snail shells. After setting up observation cameras, scientists discovered that the island's capuchin monkeys had started using large flat stones to hammer open snails, clams, fruit and nuts – the monkeys here use stones as tools.

“Don’t be surprised if you see the next Planet of the Apes set on Coiba,” jokes Solanilla, as we round a corner heading towards a set of steep stone steps. We begin climbing the stairs, led by Madrid, and with every one tackling the elevation at their own pace. When I reach the top, I take a moment to whip out my phone and capture the whimsical view that lies directly in front of me.

Coconut palms sway lazily and the blue sky above is peppered with fluffy white clouds. Our fishing boat bobs just off the shoreline, waiting to take us to explore the deep blue ocean. It is the definition of paradisiacal.

Just then, I hear a noise, one that’s unlike anything I’ve heard before. Deep and guttural, it's quite terrifying. I look around, only now realising that the rest of the group have gone on ahead of me. My eyes dart from left to right, scanning for movement. As I recall the tales that Madrid has shared, the hairs on my arms stand to attention and I feel an uneasy sensation in the pit of my stomach. I’m about to shout out for the group when I catch sight of it – a hairy bearded howler monkey, bounding through the trees. My whole body relaxes as I realise that’s what the sound was – the cacophonous cry of this hunched mammal echoing through the trees.

I sigh and give myself a shake, almost laughing out loud at my overactive imagination as I hurry on towards the hill where my group is gathered. Just before I reach them, the weather seems to shift. While the blue skies remain – an icy breeze drifts through the air, spreading its coldness on the back of my neck.

“Ooo, it’s getting cold,” I announce to the group as I finally catch up with them. Eight pairs of eyes regard me with surprise and one of the girls replies: “It's the hottest it's been all week.” And then, as quickly as it came, the icy chill is gone and the tropical humidity once again envelops me.

It must have just been a breeze, I think. Or was it?