They travel thousands of kilometres across west Africa to get to the southeast Nigerian city of Calabar where small boats are supposed to take them to a better life.
But these migrants aren't about to cross the Mediterranean Sea to Europe. They're aiming for a closer -- and less risky -- promised land: rich oil-producing African countries.
Symphorien Hounkanrin, 35, is originally from Ketenou, an impoverished village in Benin, and left school at the age of 11.
Other than fishing, he says "there's nothing to do there" for young people like him.
His brothers and cousins all left for oil hubs, Libreville in Gabon, or Malabo in Equatorial Guinea. Now he wants to join them.
"There's work. You can earn a lot there," he told AFP, his eyes lighting up.
"You can come back and build a nice house in the village like those who go to Europe."
The United Nations has said that contrary to common belief, more than half of all African migrants actually look for work elsewhere on the continent.
Like Gabon, which is home to just 1.8 million people, sparsely populated oil-producing countries attract a plentiful supply of foreign workers every year.
They come from Burkina Faso, Mali, Nigeria and Benin, disregarding the risks for the prospect of opportunities.
"No-one knows how many leave nor how many die" en route, said Nassirou Afagnon, from the International Organization for Migration (IOM) in Benin.
Few statistics are available.
Because there is free movement between member states of the west African regional bloc ECOWAS, it is easy for would-be migrants to reach Calabar by road.
The peaceful port city off the Gulf of Guinea lies only a few miles by sea to their intended destinations.
Standing in front of a small jetty scattered with rubbish, an employee of the Maritime Union promises potential clients a safe trip and no identity checks.
Seven thousand naira ($22, 20 euros) is enough to get to the port of Limbe in neighbouring Cameroon. From there, another boat to Gabon costs 15,000 CFA francs ($25, 23 euros).
For the same trip from Calabar, some operators charge up to 350,000 CFA francs per migrant, according to those who have made the journey in Gabon.
Traffickers are well-established along Marina Bay in central Calabar, where they're called "businessmen".
During the day, they take fishermen and merchandise to other Nigerian ports legally.
But during the night, their boats carry a silent human cargo.
At the end of February, Joe Abang, the justice minister of Cross River state, of which Calabar is the capital, raised the alarm.
He said Calabar had become "the transit haven for traffickers" to "perpetrate their nefarious activities" because of a crackdown against smuggling in neighbouring states.
"They use the ports and various creeks in the area to transport their victims to countries like Cameroon, Equatorial Guinea and Gabon among others," he added.
"But I have bad news for them. Cross River State has never been, and will never be, a hiding place for criminals."
Overlooking the lagoon, the city's museum has a reminder about where Calabar's wealth came from in times gone by.
Ironically, the city was a major trading port for slaves to the New World between the 17th and 19th centuries.
The local Efik people captured men from tribes in the interior and sold them to Europeans. At the city's museum, the Efik are described as skilled negotiators.
"We used to sell our people to Caucasians for centuries, we have integrated slavery in our mindset," said Bassey Ndem, a former minister in Cross River.
"But now, they are begging to enter the boats."
The trip from Calabar to Gabon and beyond takes several days and according to the IOM's Afagnon is "very well organised by unscrupulous 'agents' who meet the migrants at every stage".
But it is also fraught with danger, even if it is not publicised as much as the Mediterranean crossings. Overcrowded boats frequently capsize.
One night last January a young man from Symphorien's village was lost at sea. His parents, who were waiting for him in Gabon, have not heard from him since.
"His mobile lost its signal not long after leaving Calabar and there's been nothing since. The boats break often," said Symphorien, sounding matter-of-fact.
The local immigration department is often powerless against the trafficking of migrants, which is helped by porous maritime borders.
"In most cases they are not detected," admitted one officer, asking not to be identified.
"They adapt their routes and we don't have enough boats to stop the smugglers in the creeks."
Children are targets of the people smugglers, who come to find them in their country of origin and promise their families they will be sent to school.
But once arrived at their destination, so-called "aunties and uncles" make them work as domestic helps or street vendors, said the immigration agent.
"Actually," he said, "it is slavery" -- and a subtle reminder of the not-too-distant past.