With snow-capped peaks tumbling towards the turquoise waters of the Caribbean, the Sierra Nevada de Santa Marta National Park is one of the jewels in Colombia’s tourism crown.

But behind the picture-postcard views lies a more sinister reality.

Armed groups are holding local businesses to ransom and terrorising Indigenous communities.

The signing of a 2016 peace deal between the Colombian state and the Revolutionary Armed Forces of Colombia (FARC) ended more than half a century of war and helped propel a country long associated with druglords and rebels onto the global tourism stage.

Since then, thousands of visitors have poured into the Sierra Nevada each day, trekking through pristine jungle to white-sand beaches or climbing towards Colombia’s mountaintop Lost City, which predates Peru’s Machu Picchu.

Few notice the men in camouflage watching from a distance.

They are members of the Self-Defence Forces of the Sierra Nevada (ACSN), a group of former paramilitaries that controls cocaine trafficking routes in the region and is also involved in illegal gold mining.

Extortion has become another lucrative business for the group. The “Conquistadores”, as ACSN members are often called, demand a cut of the earnings of hotels, tour bus companies and Indigenous communities, whose hand-woven hammocks and bags are snapped up by visitors.

“We are afraid and anxious about the future,” said Atanasio Moscote, the governor of the Kogui Indigenous people, who live high up in the Sierra Nevada de Santa Marta National Park, which the Kogui consider “the heart of the world”.

In February, the government closed Tayrona National Park, a UNESCO World Heritage Site overlooking the Caribbean, for more than two weeks following threats against park rangers, allegedly issued by the ACSN.

Authorities have accused the group of pressuring Indigenous Wayuu residents in the park to resist a crackdown on illegal activities such as logging.

Together, Tayrona and the Sierra Nevada national parks received more than 873,000 visitors last year.

The influx of tourists marks a dramatic shift from the 1980s and 90s, when the region was a battleground for brutal clashes between paramilitaries and FARC rebels.

Ten years after FARC laid down its arms, the ACSN – founded by a paramilitary leader who was later extradited to the United States – holds sway in much of the area.

In recent months, Colombia’s biggest drug cartel, the Gulf Clan, has tried to muscle in, vying for control and prompting clashes with the ACSN.

Caught in the middle are Indigenous communities “who don’t speak Spanish, and who live off their crops and their traditional knowledge”, said Luis Salcedo, governor of the Arhuaco people, who also live in the Sierra Nevada.

Gustavo Petro, Colombia’s first left-wing president in modern history, included the ACSN in his bid to negotiate the disarmament of all armed groups in the country.

But four years after he launched his “Paz Total” (total peace) campaign, the ACSN still dominates the Santa Marta area, said researcher Norma Vera.

Extortion has now emerged as a key issue in the campaign to elect Petro’s successor in polls starting on May 31.

The Ministry of Defence says it has received more than 46,000 extortion complaints since 2022.

Omar Garcia, president of the hotel association in the coastal city of Santa Marta, a gateway to the Sierra Nevada, said he fears for Colombia’s fragile tourism boom.

“Any news affecting the image [of a destination] and visitor safety makes tourists think twice,” he said.