It's a warm, sunny, late summer day on the Drina River near the village of Kozluk in Bosnia and Herzegovina.

Although the river can reach a depth of up to 1.5 meters (almost 5 feet) in places, it is mostly only knee-deep around here, which means it's almost possible to wade from one bank to the other.

Three young men have just emerged from the river; their shorts and T-shirts are still wet.

"We just swam over," one of them tells DW. He says his name is Aman and that he is 20-years-old. "We saw that no one was on the other side, so we set off. In some places, the river bed is dry. We got wet, but the sun is shining, so we'll dry off quickly," he says, smiling. All three laugh.

Well-worn refugee path

The three young men come from Morocco and are on their way to western Europe. They traveled first to Turkey and then to Greece. From there, they crossed over into North Macedonia and on to Serbia. Until just a few days ago, they were in a reception facility near Belgrade.

The Drina River is part of what is known as the "Balkan route" used by many migrants en route to northwestern Europe. This land route usually begins in Turkey and then winds up through the Balkans through either Bulgaria or Greece.

Volunteers on hand to help

Here, at the Drina River, which forms a large part of the border between Serbia and Bosnia-Herzegovina, the three young men waited until the coast was clear and for a good opportunity to cross. "No problem, no problem," they say at the end of almost every sentence.

One of the three sustained minor injuries to his legs while crossing the river. A volunteer from a Bosnian Red Cross team that happened to be in the area when they came out of the river, bandages the young man's right knee.

The Red Cross team patrols the river bank regularly on the lookout for migrants in need of food or medical assistance.

Sometimes, says team leader Mladen Majstorovic, they are called on by the border police.

His colleague, Darko Jovanovic, says that the Red Cross team treated a total of 800 refugees here and handed out almost 3,000 meals in the first eight months of the year.

Migrants have drowned in the river

Every day, dozens of migrants cross into Bosnia along this section of river. Hardly anyone stops them.

This part of the border is patrolled by an insufficient number of Bosnian border guards. Hundreds — perhaps even thousands — of guards would be needed to patrol the entire region.

The situation is so dramatic that at some border crossings, there is only one officer processing all entries and departures at a time.

Despite claims to the contrary, the Balkan route was never entirely shut down. Indeed it has been particularly busy again for quite some time now — especially along the Drina.

There have been a number of tragedies on the route in recent years. The last one took place just a few weeks ago when at least 10 migrants drowned in the Drina close to the Serbian town of Ljubovija on August 22 when a completely overcrowded inflatable boat capsized.

The people were apparently crammed onto the boat by human traffickers. Eighteen people managed to save themselves.

'It all seems organized'

Nihad Suljic has also noticed that the number of migrants at the Drina has risen sharply in recent months.

In addition to his regular work in the eastern Bosnian city of Tuzla, the 34-year-old is also a human rights activist who helps stranded migrants by providing them with the bare necessities.

Suljic is well known in Bosnia because he helped set up a cemetery for migrants who had been found dead in the country.

"When it comes to migration, Bosnia is once again the center of attention," Suljic told DW. "But unlike in the pandemic years and the period immediately preceding it, the human traffickers now seem to be perfectly integrated into the structures."

After crossing the border, migrants used to walk in small groups to the reception facilities or straight on towards Croatia, says Suljic, adding that migrants are now rarely seen on the streets, because the reception centers are all full. "It all seems to be perfectly organized," he says.

Migrants keep out of sight

Miroslav Radisic says much the same thing. He owns a guesthouse only a few meters from the Sepak crossing on the Bosnian-Serbian border, about 20 kilometers (12.4 miles) downstream from the city of Zvornik in Bosnia.

Radisic says that business with the refugees is booming, that everything is interconnected and everyone in the region knows it.

According to Radisic, taxi drivers wait right outside his guesthouse and negotiate with arriving migrants about prices.

"You can't get any sleep around here, with taxis coming and going all the time," he complains. "Then there are the sirens blaring. People fight over the refugees: Sometimes ten refugees arrive and 20 taxi drivers are waiting for them here."

Radisic is standing underneath the bridge over the Drina that leads to Serbia, explaining how migrants cross the border on the underside of the bridge.

"They climb onto the steel girders under the bridge and abseil down a rope hanging down on our side that no one removes — not even the officers here at the border."

When asked why this is the case, Radisic says that the border will only be hermetically patrolled when the border police get enough personnel.

Stepping up border patrols

In response to a query from DW, the border police in Bosnia and Herzegovina said that the force is monitoring the border more closely and that more police officers and members of the special security forces have been deployed. Their aim is to stop irregular migration.

"Since the beginning of the year, border police officers have registered 5,477 people who have illegally crossed or tried to cross the border," the border police said in a statement. "In most cases, human traffickers, who bring people across the Drina either in private cars or with boats, are also involved."

The three young Moroccans seem to have come to Bosnia on their own steam — at least they make no mention of human traffickers.

They say that they first want to go to the Bosnian capital, Sarajevo, and then cross the green border into Croatia near Bihac in northwestern Bosnia. They are headed for Germany.

"We cannot lead normal lives in Morocco," they say, when asked why they have made the journey. Then they get into a taxi and set off towards Zvornik.

This article was originally published in German.