Tunisian coastguards face a flimsy craft packed with migrants who keep trying to fulfil their dream of reaching Europe.
"This is your final warning: stop!" an officer shouts.
Some two dozen migrants, wearing inflated inner tubes as makeshift life preservers, look downcast as they realize the game is up.
But Fatim, an 18-year-old from the Ivory Coast who spent a year working as a cleaner in Tunis to raise 1,250 euros in smugglers' fees, said she will try again.
"I don't want to stay in Tunisia," AFP quoted her as saying. "Life here is hard."
In May last year Tunisia, just 130 kilometers (80 miles) from Italy's Lampedusa island, signed a deal with Rome, which agreed to supply economic aid in exchange for Tunisian efforts to stem clandestine migration.
"If I found another boat I'd leave again straight away -- I'll never give up," said Guinean migrant Ali, 20, after he was released at Sfax port.
In just one night early this week, the coastguard intercepted 130 African migrants, including children and babies, on four craft attempting the crossing from the central region of Sfax.
Idia Sow, a 26-year-old Guinean, said she had paid smugglers 1,560 euros for places for herself and her three-month-old baby on an inflatable boat headed for Lampedusa.
The migrants are taken back to the port in the provincial capital of the same name, their details are recorded -- and then they are released.
Officials said the coastguard lacks the resources to halt the flow.
"We're in a vicious cycle. We make enormous efforts to stop these migrants, but in the end they're released and then we find them trying again," said the patrol's commander, Colonel Major Brahim Fahmi.
"This summer we hit a record of more than 17,000 migrants (intercepted off Sfax), almost double the figure in recent years," said coastguard official Saber Younsi.
"This our role," he said. "We have to keep doing it, but there's been a worrying evolution."
The demand has created one of the few thriving new industries in Tunisia: clandestine boat manufacture.
Younsi said new smuggling networks were emerging to cash in on the surging market, with demand also coming from Tunisians who have given up hope of finding decent jobs and in some cases are emigrating as entire families.
As he spoke at Sfax port, Younsi was surrounded by piles of hundreds of captured migrant boats.
According to official figures, more than 22,500 migrants have been intercepted off the Tunisian coast since the start of the year, around half of them from sub-Saharan Africa.
Some 536 people, mostly Tunisians, have been arrested on suspicion of people smuggling.
Younsi said the authorities were struggling with limited means.
"If the same trend continues, we'll hit a point where this phenomenon gets out of control," he said.
