It is a traditional role using skills passed down through the generations, but young unskilled boys with no knowledge of the mountains are flocking to become porters in Nepal's Himalayas.
The lure of comparatively high wages is encouraging the teens to carry packs for tourists during the busy trekking season. But some experts say they are putting both themselves and climbers at risk.
Wage hikes for porters, praised by unions and advocacy groups, mean treks through the Himalayas have now become a lucrative venture for Nepalese boys, some as young as 14.
"Friends who've done portering told me it's a good way to earn money, so now I'm doing it too," says 19-year-old Tendisha, who uses just one name, during a trek down from Everest Base Camp.
"I didn't know anything about the mountains before," he adds.
Porters traditionally carry food, safety equipment and camping gear, often trekking ahead of the group, setting up camp before the trekkers arrive, or staying behind to pack up.
Some of them are Sherpas, experienced mountaineers who guide climbers through the Himalayas.
In a profession that requires local knowledge about factors such as altitude and temperature, as well as basic medical skills for emergencies, lack of experience can endanger an expedition.
And without expertise, the porters themselves are at risk of injury.
"They've never carried anything in their lives," says Jo Chaffer, a veteran guide and trekking company consultant based in Nepal.
"They have no knowledge of altitude, they have no mountain clothing, they have no mountain footwear. It's not good for them, it's not good for the clients, it's not good for the trekking industry at all."
The porters however are unlikely to complain.
"They are out there to make good, quick money, and they also feel pressure to prove themselves, so they don't object to poor conditions until several days into a trek when they're seriously injured," she adds.
Companies are hiring the youngsters as urbanisation and labour migration have drained many rural Himalayan trekking regions of the men who have traditionally worked as porters.
In a report released last year, the UK-based advocacy group Porters' Progress called Nepal's portering trade an "industry in crisis".
Their research reveals that many men are leaving the mountains, and the country altogether, to seek higher wages as Nepal's economy struggles to recover from a decade-long civil war that ended in 2006.
More than a thousand Nepalese citizens migrate abroad each day looking for work.
-- Safe trekking may depend on foreigners --
With the exodus of experienced porters, traditional practices -- such as eating garlic during an ascent to help mitigate the effects of altitude -- are disappearing.
"There used to be a tradition of older porters training younger porters," says Chaffer.
"But now, the older porters are frustrated by the swaths of unskilled young men who go to the mountains -- they don't believe the younger guys are genuinely there to learn the trade," she says.
Labour conditions for porters have long been a focus of advocacy groups in Nepal, where tourism is a leading industry and Himalayan trekking attracts an estimated 40 percent of the foreign visitors to the country each year.
Despite new minimum wage guarantees, some say the flood of young porters is being exploited.
Alonzo Lyons, a US writer and mountaineer based in Nepal, says he has witnessed crews of young men carrying overloaded packs over treacherous terrain.
"When I have asked porters out loud how much they are carrying, they all usually say 25 kilos," Lyons says.
"It's only later when I ask again in private that they change it to 40, even 60 kilos. Then they admit they were encouraged by their employers to lie," he says.
Dhiraj Tamang, 22, says he often carries 45-kilogramme packs during treks, without proper equipment such as walking sticks, and works alongside porters who know little of the hazards of mountaineering.
"There's no uniformity in terms of wages and the agencies don't usually provide sufficient gear and equipment for us," says Tamang, a porter for three years.
"If it's a trek with camping, things are likely to go wrong because you are talking about a huge logistical operation."
A porter's minimum wage is around $8 a day, but trekking guide Sonam Sherpa says that he has worked on crews where porters receive less than a third of that.
"The young guys who know less about the work also know less about their rights," he says.
With corruption and political instability still plaguing the country, there is little hope of better government monitoring or enforcement deep in the mountains.
As a result, responsibility to make trekking safe might in part fall on foreign visitors themselves, Chaffer says.
"Tourists coming to visit the Himalayas need to pay attention to their staff, talk with their porters, ask them about their lives," she says.
"It not only makes for a pleasant, genuine experience in Nepal, but it can let them understand who is supporting them, and potentially alert them to danger."
In May, European climbers were involved in a brawl with a group of Sherpas who had been rigging up ropes for their clients on the upper reaches of Everest.
The fight, essentially over climbing rights, shocked the mountaineering community and caused a damaging rift between Western climbers and their Nepalese guides.