The traffickers often move by bicycle, criss-crossing Havana with the week's digital stash tucked in small slipcases.
They ply their trade in the backs of cellphone repair shops, or climb stairs in creaky tenements to make their drops at clients' doors.
In internet-starved Cuba, these black-market suppliers push a coveted product — curated offerings from the World Wide Web for $2 to $3 US.
Cubans call it "El Paquete Semanal," or the weekly package.
It comes in the form of a one-terabyte re-up of newly pirated information each Monday. Think international movies, newspapers, the latest Afro-Cuban hip-hop tracks, Korean and Australian soap operas, mobile apps, Wikipedia pages, PDFs of National Geographic magazine, the entire run of Netflix's House of Cards, even classified ads from Revolico, Cuba's take on Craigslist.
"It's what I call our national internet," says Isbel Diaz Torres, a Havana package subscriber who consumes American culture through reality-TV cooking shows like Chopped and Top Chef.
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"You have your films, your music, your articles," says Torres, 40, drinking a malted cola on a steamy afternoon in March.
El Paquete was how Torres's boyfriend caught February's Oscars ceremony.
The clandestine service was also how Carlos Alejandro Rodriguez Halley, a 28-year-old actor and restaurateur in the Cuban capital, watched the film The Revenant before some of his American friends.
"If you want to know about hockey scores, probably it's in the package," he said between drags of a Hollywood brand cigarette. "Someone in this corner, in this block, I bet you every week they pay to get the package."
An 'offline internet'
It's not just about entertainment. The weekly digital delivery reportedly informed many Cubans in 2011 about the death of Osama bin Laden via foreign news.
The "offline internet" trade, as locals describe it, is not strictly legal. The state controls Cuban news and entertainment media. But some speculate the Castro regime turns a blind eye to the underground sneakernet, reasoning it keeps the public desire for widespread internet access at bay.
"You have everything you want to find in the internet on El Paquete," Torres says.
"Everything," he adds, "except for communication."
It's one way the package falls short as more locals yearn for their country to come online.
Digital dark ages
U.S. President Barack Obama urged the Cuban government during his visit here last month to emerge from the digital dark ages.
"New technology has come and we need to bring it to Cuba," Obama said.
The isolated nation's internet penetration rate could be as low as five per cent, according to the global democracy and civil-liberties watchdog Freedom House.
Wi-Fi hot spots remain elusive, though several parks allow for access via pre-paid scratch cards. Even then, loading times are agonizingly slow. It's also expensive, costing $2 for a one-hour Wi-Fi scratch card in a city where average wages are about $20 a month.
One young entrepreneur, who did not want to give his name, admitted to hoarding scratch cards, then jacking up prices to $3 for the resale market. Another of his odd jobs, he said, is as a dealer of El Paquete.
"In my opinion, it's too difficult to get connected to Wi-Fi here," he said of the often spotty service. "So many people, like me, for example, have lost all their credit while waiting, trying to get connected."
Still, pass through a park in the central La Rampa ward at night, and you may see dozens of faces illuminated by phone and tablet screens, checking Facebook or video chatting with relatives abroad.
"It's kind of a crazy situation. It's very crowded, and you sometimes have people sitting next to you, talking about very personal stuff. Family stuff," says Jorge Duany, a Florida-based Cuba scholar who tried the island's Wi-Fi for the first time in February.
Internet minutes are precious.
A common practice is to load up an email inbox, then disconnect to read and draft replies offline. Users log back in once they're ready to batch-send responses.
Few people will waste time loading up the latest viral YouTube video.
That's what El Paquete is for, says Julio Alberto Hernandez, a 22-year-old courier for a mini digital-media empire started by Elio "El Transportador," or the transporter. (A competing package kingpin in the city goes by the moniker Dany "El Paquete.")
On a park bench near the University of Havana, Hernandez got downright philosophical.
"If entertainment is a necessity to Cubans," he said, "then the package is a necessity."
Swirling an icy cherry granizado cocktail, he broke down the business model.
Subscribers who receive the latest terabyte either keep it for several hours to browse and download the entire contents, or parcel it out onto smaller-capacity USB thumb drives for further distribution.
Monday clients pay a premium for the latest content, sometimes $6 US. Prices drop throughout the week. Most will pay $2.
But other logistics of the operation remain somewhat shrouded. How, for example, are the packages assembled so quickly every week?
Reached by phone in the U.S., where he temporarily lives, El Transportador, whose real name is Elio Héctor López, said "nobody understands the answer."
But he acknowledged his family in the States has premium internet service, allowing for faster downloads.
"If I have the package, I have friends in the neighbourhood come to my house [in Cuba]," just to copy material for dispersal. "They bring their own USB flash drives," he said.
A report by Vox suggested that some El Paquete collating happens in Cuba, and that illegal satellites disguised as rooftop water tanks might accommodate big downloads.
Hernandez, the package runner in Havana, said that at least some downloading happens at a large Cuban tourist hotel with good Wi-Fi.
He estimates that the Transportador network has 80 major paquete subscribers in Havana. The digital data is also smuggled outside the capital to rural areas.
"Of course we send this to other provinces. By car, bus, plane, whatever," Hernandez said.
López, his boss, was warned by authorities not to distribute anti-regime propaganda through the package. There's another restriction: "No hay pornografia," Hernandez said.
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For now, at least, El Paquete is apparently tolerated by the government, though López denies rumours that the regime is secretly behind the movement.
"They don't stop the package, but nobody in the government helps to make the package," López insisted. "This is something started from the people."