They aren’t supposed to be here. Their parents would be angry. But the boys are tired of the crowds, the smog, the construction that devoured their makeshift soccer field.

So they crossed the highway on a recent afternoon, hopped a concrete border and weaved their way through goats and tires and trash until they could see the waves — the same waves that killed Fadilou.

No one saw it happen. They didn’t realize their friend had waded into the ocean two years ago until an older man — maybe an Italian tourist — pulled his body from the water.

“All of a sudden he was gone,” said Madiop Diop, 16.

The speed of growth in sub-Saharan Africa, the most quickly urbanizing place on Earth, is posing an insidious threat to the overwhelmingly young and poor population. Excavators, cranes and cars are taking over spaces where children once gathered, shrinking safe havens for some of the region’s most vulnerable residents.

The economic shift comes at a deadly cost in Senegal, a former French colony of 16 million on the continent’s west coast. 

As empty lots vanish and traffic clogs roads, authorities say more children are heading to the beach with little to no supervision. At least 50 people drowned last summer in the capital city of Dakar, up from an average of 10 in the previous three years, the latest numbers show. Most of the victims were younger than 14. 

Drowning kills nearly six of every 100,000 people in Senegal, according to the World Health Organization. That’s about six times the rate in the United States, France or Spain.

The government is training hundreds more firefighters on water rescue in response to the problem, but Dakar’s neighborhoods are responsible for hiring lifeguards, and they’re struggling to keep up with the rising number of swimmers. 

Some lack the money to stay properly staffed, said Papa Magalle Samse, chairman of the beach association in the Golf Sud district. Most kids cannot pay for swimming lessons. 

“Spaces of leisure are transforming into houses,” he said. “The adults aren’t thinking of the children. They have nowhere to go.”

What politicians cast as progress can feel suffocating to children in rapidly developing nations, who tend to live in cramped homes and yearn to roam. They don’t have smartphones or iPads. Adults occupy televisions with soccer matches or Indian soap operas dubbed into the local language. Playgrounds are scarce. 

The problem is especially pronounced in Africa, where the number of city dwellers is  projected to double over the next 25 years, the number of people under age 24 is nearly twice the size of the U.S. population, and people drown at a higher rate than anywhere else.

Economists used to think children in remote villages were worse off than their peers in cities, where education, health care and jobs are more accessible, said Laurence Chandy, director of data, research and policy at UNICEF.

That assumption is crumbling. Unfettered sprawl is cranking up pollution, straining safety nets and widening the standard-of-living gap between children whose families can afford space and those who are forced to navigate an increasingly dangerous obstacle course.

Senegalese President Macky Sall’s signature quest to supercharge growth has spawned a new stadium, convention center, train line and airport. Residents joke that they notice more construction every day.

Critics say it’s happening without a mindful blueprint. High-rises sprout on lots designated for one-story homes. Codes to protect ocean views are not enforced. Children dash through hard-hat zones.

“The lack of planning creates these urban hazards,” Chandy said.

Dakar has one playground, public garden or park for every 82,000 inhabitants, according to ImagiNation Afrika, a nonprofit organization that began counting this year. (Washington has 1.73 per 10,000 residents, not including federal parkland.)

“In the name of urban development, we have destroyed open public spaces and polluted the ones that still exist,” ImagiNation Afrika founder Karima Grant said.

Which leaves the beach. 

Senegal has 330 miles of coastline on the Atlantic Ocean. Neon-colored boats, volcanic rocks, pink sunsets and cheap beer attract sunbathers and Instagram attention. People turn the sand into a gym, unfurling yoga mats and dropping into push-ups.

The scene is a source of national pride and serious income, said Ibrahima Sarr, director of investment at the Ministry of Tourism. Hilton, the hotel chain, might break ground here next year, he said, while the government aims to triple the annual number of tourists to 3 million by 2023.

As the crowds swell, Senegalese firefighters are running drills with French rescuers, zipping around in red Zodiac boats and pulling one another out of the water. But it’s up to the neighborhoods to secure their own shores.

“Communities must take charge of the matter,” Sarr said.

In Golf Sud, where Fadilou drowned, officials are raising money to hire more lifeguards before the summer heat spikes. They’re seeking donations from companies and enlisting volunteers to patrol the beach and talk to children about the risk of paddling out too far.

Still, residents say, the challenge feels daunting. Extended families often share small homes. Formal child care is rare. Babies and toddlers demand attention. Older kids are on their own.

Fadilou was 13.

Nine people live in his old concrete house, a 10-minute walk from the sea. His father sits next door, chatting with neighbors in this tightknit community.

Papa Abdulaye Diop, 63, said he wants the government to protect outdoor space and build playgrounds.

Taxis rumble outside the door. Traffic snarls the block. Children kick a ball below an overpass.

“If there were more yards, more space in our district,” Diop said, “the problem could be solved.”

Talking about his son is painful, he said, wiping his eyes behind his glasses.

Fadilou was polite and full of energy. He dreamed of playing soccer professionally. A family photo shows him grinning in a green and white Adidas jersey. 

He didn’t know how to swim. 

The boy hadn’t mentioned spending much time at the beach — but he had complained about someone buying the lot where he liked to play soccer.

Then men showed up at their house, saying: I’m so sorry. 

Diop stops the story there.

“I can’t go on because it hurts me too much,” he said.

Fadilou’s friends in the neighborhood stayed away from the ocean for months. The memory haunted them. They feared the waves.

But the desire to break into a sprint returned. To kick the ball as hard as they could. 

“We don’t swim anymore,” said Madiop, sitting in the sand one afternoon last month. 

He won’t even go in, he said, even though a lifeguard at a local pool taught him how to stay afloat.

The teenager and three other boys sneak to the beach with their worn orange soccer ball and a puppy named Ladi. They practice at a safe distance from the water, enjoying the breeze on their faces.

After school on weekdays, it’s not crowded. It’s an escape. 

There’s no lifeguard in sight.

Khadidiatou Ba contributed to this report.