The golden beaches of Cayo ...
The golden beaches of Cayo Cruz lie at the end of a long path through a nature reserve. It is an idyllic stretch of Cuba's northern coast but this is key territory in the fight against international drug-tafficking.
Cuba sits right between the world's major narcotics producers in South America and the biggest market for those drugs, the United States.
The island has served as a bridge for traffickers in the past but in recent years it has been a barrier to the illegal trade.
"We used to see a lot of suspicious boats here," Ardoldo Cisneros Pena recalls of the 1990s. He is chief border guard in Cayo Cruz, where we were recently given rare access.
"There were almost daily drops into the sea," he says. Small planes would bombard Cuban waters with packets of drugs, for speedboats to whisk to the US.
Today, the scene is tranquil. A young border guard scans the horizon from a mint-green watchtower. A stone slab below reads "They shall not pass!" and "Viva Fidel!".
It was Fidel Castro, then president, who acknowledged a surge in the use of Cuban waters by drug-traffickers in 1999. There was a nascent narcotics market too, as smugglers' packages began washing up on the coast.
The government was compelled to act against what Mr Castro calls a "mortal venom".
"We have more resources now, there is a helicopter for the border guards and more commitment from the interior ministry, the military and the Cuban people too," Lt-Col Cisneros explains.
Operation Ache, as the crackdown was known, also installed a new radar and recruited hundreds of unpaid "collaborators", trained to keep their eyes peeled for suspicious parcels along the shore.
The drugs planes have now gone and the main threat today is from speed-boat smugglers attempting to traffic marijuana north.
"They try to escape us but if they can't, they try to dump the drugs because they know this activity is very heavily penalised here," explains Lt-Col Mago Llanez Fernandez, who heads the team responsible for intercepting the smugglers at sea.
He admits that up to 60% get away. Securing any abandoned narcotics is the priority here.
But as the boats flee, Cuba now passes real-time data to the US coastguard so they can pick up the pursuit. It is rare teamwork for two old, ideological enemies.
"I think this is important for Cuba, because we're preventing the drugs reaching here, but it's also very important for the US and other countries in the area," Lt-Col Llanez points out.
With its very heavily policed society, it is no surprise Communist Cuba is not a big drugs market itself.
Scarce supply means even a joint of marijuana can cost up to a week's wage ($5) for a state worker. But some smugglers have begun to see potential here.
"We've seen a rise in attempts by Cuban Americans to bring drugs in, especially marijuana, because the prices are high here," says police investigator Yoandrys Gonzalez Garcia.
"It's not a huge amount but it concerns us and we're increasing our efforts to fight this."
Between January and June this year, 24 attempts to traffic narcotics through the island's airports were foiled, and these figures put Cuba on course to double the interdiction rates of 2010 and 2011.
The drugs were mostly destined for sale in Cuba.
Police point to a surge in air traffic with the US since President Barack Obama removed travel restrictions for Cuban-Americans. Lifting limits on remittances has also given some Cubans on the island greater spending power.
But the US is not the only smuggling source.
Boris Adolfo Busto was arrested at Havana airport for drug-trafficking. His group was bringing in drug "mules" from Ecuador, with up to a kilo of cocaine in their stomachs.
"There was a Cuban guy involved and he said he could sell everything here, he said it'd be easy," Busto recalls when we meet at Havana's Condesa prison.
He is serving a 23-year sentence.
"I think the authorities are very efficient," he says forlornly, adding that "dozens and dozens" of other smugglers have since joined him behind bars.
Cuba has called for a formal co-operation agreement with the US to help stamp out smuggling in both directions.
It already shares intelligence with European governments, and receives funding and training.
"Our communication at sea gets good results but sadly we can't say the same about air traffic," Mr Gonzalez police investigator complains of the Americans.
The US and Cuba severed diplomatic ties more than five decades ago.
But officials on the ground acknowledge Cuba's contribution to the common war on drugs.
"[Without] a strong counter-drug stance, Cuba would be a prime area for drug smugglers, but its efforts are very effective," says Louis Orsini of the US coastguard, adding that the US would find it "really challenging" if Cuba became a direct conduit for illicit narcotics.
Today, though, the policy is zero tolerance and the interior ministry says nine tonnes of drugs were seized from traffickers last year and incinerated.
Most were destined for the US market and beyond.
BY BBC News