The text contains details that may be disturbing to some readers.
The most shocking thing for Jonathan, who endured six harrowing months living and working underground in an abandoned South African gold mine, was the child abuse he witnessed.
Some children are recruited as cheap labor, but others are brought specifically for sex, activists claim.
Jonathan, now in his late 20s, emigrated to South Africa, lured by the promise of easy money working in one of the dozens of abandoned mines that had been closed by multinational companies because they were no longer commercially viable.
We will protect his identity because he fears retaliation from brutal criminal gangs in illegal mining for speaking to the media.
Details of what the young people went through emerged after the deaths of dozens of illegal miners near the town of Stillfontein last year when a mine was blocked by police.
In a calm and collected voice, Jonathan describes the heat, long hours, and limited food and sleep opportunities that have begun to take their toll on his body.
But what remained in his permanent memory was what happened to the underage miners in the mine where he worked.
"I saw kids in the mine - teenagers actually, 15-year-olds, 17-year-olds.
"Others would sometimes take advantage of them. It was a bit scary and I didn't feel comfortable with it."
She says they were raped by adult miners who promised them the gold they dug up in exchange for sex.
"If that kid is desperate for money, then they'll take a risk."
Jonathan describes how children would often ask mining teams for protection, "but the team would make their own terms."
Sex also served as punishment if teenagers failed to complete a task for their team.
Jonathan says that the children in the mine where he worked were all strangers and didn't understand what they were getting into.
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Mining researcher and activist Makotla Sefuli confirms this.
He says criminal gangs are targeting children specifically to work in illegal mines across South Africa.
Many of them were kidnapped from neighboring countries and smuggled.
They receive unfounded promises that they will be found employment in official mining.
"They take away their passports as soon as they arrive in South Africa...
"It's an open secret that these young guys are being abused," Sefuli says.
The BBC spoke to miners working in at least two other illegal mines who told us they had seen children being abused in the shafts where they worked.
Tšepo (not his real name) says he saw older men forcing young boys to have sex with them underground.
"In some cases they did it for money."
"Some are hired solely for that purpose, because of the financial incentive that may come with having sex underground."
The abuse, he adds, left a deep mark on these children.
"They change their behavior and have problems trusting others."
"They don't want you to come near them because they can't trust anyone anymore."
Illegal mining in South Africa made headlines last year after clashes between police and miners at the Buffelsfontein gold mine, near the town of Stillfontein in the North West Province.
Authorities have tried to curb illegal mining, which the government says cost the South African economy $3,2 billion in lost revenue last year.
In December 2023, authorities launched an operation Close the Hole, or "plug the hole", saying they will be tougher on gangs.
As part of the operation, police restricted the amount of food and water being lowered into the Stillfontein mine, in order, as one minister put it, "to flush out the illegal miners."
Officials said people were refusing to come out for fear of being arrested.
Soon, footage from inside the mine itself began to emerge, showing dozens of emaciated men begging to be saved, as well as rows of body bags.
In the end, the court ordered the authorities to rescue these people.
Among those brought to the surface were many who claimed to be minors, but since a large number of them were migrants without documents to confirm their age, the authorities performed medical tests on them to make that assessment.
In this way, the Ministry of Social Development (DSD) confirmed that 31 of the rescued miners from Stillfontein were children.
All the children were Mozambican citizens and on November 27, 27 of them were repatriated.
The organization "Save the Children of South Africa" helped translate some of the conversations between the underage miners and their rescuers.
"They have been through trauma, because some of them have also seen others being sexually exploited," Gugu Xaba, the charity's executive director, told the BBC.
"The very thought that they might never get out of there mentally destroyed those children."
"The adult miners would start by seducing them, pretending to like them."
She says that the children were then forced to perform sexual acts on adults and then raped, day after day.
"We discovered that the adult male had three or four boys to whom he did the same things."
Ksaba says that mining gangs recruited children because they are easier to manipulate and cheaper.
"Children don't understand when you tell them, 'I'll pay you a dollar a day.'
"Adults sometimes refuse to work, but children often have no choice, and that's why it's easier to force children to work."
"It's easier to take a child who can't handle it on their own and take them down there."
In addition to children being exploited financially, she says there are gangs that recruit children solely for sex.
Many illegal miners spend a month underground, rarely coming to the surface.
Markets are springing up underground to provide them with everything they need.
"Most child trafficking is for the purpose of exploitation as sexual slavery."
"There are also pimps who take money, which means that child is being used as a commercial sex worker every day."
The BBC asked the police and DSD whether anyone would be charged over the sexual abuse allegations.
They did not respond to our inquiries.
A source working on the Stillfontein miners' cases said many of the children did not want to testify.
And the illegal mining industry continues to flourish.
And with an estimated 6.000 abandoned mines potentially available for exploration, it's a job that won't be finished anytime soon, putting thousands of vulnerable children at risk.
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