PORLAMAR, Venezuela >> On the outside, the San Antonio prison on Margarita Island looks like any other Venezuelan penitentiary. Soldiers in green fatigues stand at its gates. Sharpshooters squint from watchtowers. Guards cast menacing glances at visitors before searching them at the entrance.

But once inside, the prison for more than 2,000 Venezuelans and foreigners held largely for drug trafficking looks more like a Hugh Hefner-inspired fleshpot than a stockade for toughened smugglers.

Bikini-clad female visitors frolic under the Caribbean sun in an outdoor pool. Marijuana smoke flavors the air. Reggaeton booms from a club filled with grinding couples. Paintings of the Playboy logo adorn the pool hall. Inmates and their guests jostle to place bets at the prison’s raucous cockfighting arena.

“The Venezuelan prisoners here run the show, and that makes life inside a bit easier for us all,” said Fernando Acosta, 58, a Mexican pilot jailed since 2007. His cellmate, a Congolese businessman, had hired him to fly a Gulfstream jet that prosecutors accuse them of planning to use for smuggling 2 tons of cocaine to West Africa.

It is not uncommon for armed inmates to exercise a certain degree of autonomy in Venezuela’s penitentiaries. Prisoners with BlackBerrys and laptops have arranged drug deals, abductions and murders from their cells, the police say, a legacy of decades of overcrowding, corruption and insufficient guards.

But San Antonio prison, renowned on Margarita Island as a relatively tranquil place where even visitors can go for sinful weekend partying, is in a class of its own.

The island itself is a departure point for drug shipments into the Caribbean and the United States, and the traffickers arrested here often end up in this prison, effectively overseeing life behind its walls with a surreal mix of hedonism and force. Some inmates walk the prison grounds grasping assault rifles.

“I was in the army for 10 years, I’ve played with guns all my life,” said Paul Makin, 33, a Briton arrested here in Porlamar for cocaine smuggling in 2009. “I’ve seen some guns in here that I’ve never seen before. AK-47s, AR-15s, M-16s, Magnums, Colts, Uzis, Ingrams. You name them, it’s in here.”

Inmates say they owe their unusual privileges to a fellow prisoner, Teofilo Rodriguez, 40, a convicted drug trafficker who controls the arsenal that awes Makin. Rodriguez is the inmates’ top leader — a “pran” as alpha prisoners are called.

Rodriguez also goes by the moniker “El Conejo” (The Rabbit), which explains the proliferation of the pran’s trademark throughout the prison: paintings of the Playboy logo.  

Inside, opportunities flourish for inmates to make money. Visitors from the island, a palm-fringed getaway destination, line up on weekends to place bets at the prison’s cockfighting arena, generating gambling revenue.

Other visitors, aware that guards search upon entering but not exiting, go inside to buy drugs. Prisoners and visitors alike make use of an alley between cells to smoke marijuana and crack cocaine.

Venezuela’s government recognizes the problems within its prisons, where fighting between gangs controlled by prans like Rodriguez contributes to a high number of killings. Human rights researchers found that 476 prisoners — about 1 percent of the nation’s entire prison population of 44,520 — were killed last year alone.

Hoping to tackle the violence, overcrowding and other systemic issues, the government vowed in 2006 to spend $1 billion to “humanize” prisons. President Hugo Chavez singled out San Antonio prison for special attention on his Sunday television program in December 2009, celebrating the construction of a new 54-unit women’s annex here.

But human rights groups say corruption and institutional disarray have stymied efforts to improve conditions in many prisons. The nation’s Institute for Penitentiary Studies has had about 1,000 graduates since the 1990s, but fewer than 30 of them work in prisons, depriving the system of professional guidance and expertise.

A series of inmate takeovers in recent weeks has underscored the troubles. In April, inmates outside Caracas took 22 officials hostage, including the warden, protesting a tuberculosis outbreak. The weeklong standoff ended when authorities agreed to replace the warden. In May, inmates at another prison took its warden and 14 employees hostage for 24 hours to protest what they called mistreatment.

“The state has lost control of the prisons in Venezuela,” said Carlos Nieto, director of Window to Freedom, which documents rights violations in Venezuelan prisons.

Luis Gutierrez, the warden at San Antonio, refused to discuss the prison he nominally oversees.

On weekends, the ambience inside, bursting with spouses, romantic partners and some who simply show up looking for diversion, almost resembles the island’s beach resorts.

Prisoners barbecue meat while sipping whisky poolside. In some cells, equipped with air conditioning and DirecTV satellite dishes, inmates relax with wives or girlfriends. (Venezuela, like other Latin American countries, allows conjugal visits.) The children of some inmates swim in one of the prison’s four pools.

Prisoners boast that they built these perks themselves, with their own money. And while San Antonio can hardly be considered safe — a grenade attack in the infirmary killed seven last year — inmates argue that compared with other Venezuelan jails, peace often prevails.

“Our prison is a model institution,” said Ivan Penalver, 33, a convicted murderer who preaches at the prison’s evangelical Christian church.

The inmates’ chief, Rodriguez, interviewed as bodyguards shucked oysters for him, attributed these distinctions to his rule. A mural at the prison depicts Rodriguez as conductor of a train, accompanied by gun-wielding subordinates, barreling toward a snitch hanging from a noose.

“There’s more security in here than out on the street,” said Rodriguez, a thick-necked long-termer who barks orders into a cellphone. Asked about his ambitions after incarceration, he said he would consider politics.

“Not to become president, because that’s too far into the ocean,” he said. “Maybe mayor.”

Until then, life under his watch hews to its own code. Parties include rap groups invited to perform inside. Though separated by a wall, the 130 inmates in the women’s annex mingle freely with the male prisoners. Some form romantic attachments, living together as they would outside.

In parts of the prison, something approaching normalcy even prevails.

One prisoner with a camera and a laptop serves as photographer, taking pictures of fellow inmates and Photoshopping them into montages, like one in which they’re seen leaning against a Hummer. A barber cuts hair. A food stand called McLandro’s sells snacks. The club’s reggaeton blares day and night. Roosters crow at dawn.

“I find it hard to explain what life is like in here,” said Nadezhda Klinaeva, 32, a Russian serving a drug trafficking sentence in the women’s annex. “This is the strangest place I’ve ever been.”