A photograph Lin En takes of his fellow "iron butt" travelers posing outside a train en route to Tibet.
Hong Kong CNN  — 

Lin En could have easily reached his destination in six hours had he caught a flight.

But during a trip earlier this year, the 23-year-old opted for a bus ride that took three days to cross from Xinjiang, in China’s northwest, to Astana, Kazakhstan’s capital.

Make no mistake. There was no premium in-bus entertainment, first-class dining or specially designed ergonomic seats on offer that made the ride particularly enjoyable.

The journey was a grueling one. The tens of hours Lin spent strapped upright to his seat gave him unbearable back pain, as he later testified in a vlog on Chinese social media platform Xiaohongshu (Little Red Book).

But he kept doing it again and again. Over the past year, Lin has made several similar trips relying solely on ultra long-haul bus and train rides to get to his chosen destinations.

He isn’t alone. A growing group of Chinese travelers are now turning to extreme forms of transportation for their vacations.

They call themselves “iron butt” travelers – inspired by the amount of time they spend traveling on uncomfortable seats that make flesh start to feel like metal.

Lin took this bus for his journey from China to Kazakhstan.

Known as “tieding” in Mandarin Chinese, the trend has drawn 19.8 million clicks with its #ironbutttravel hashtag. “Those with iron butts enjoy the world first” is their motto.

Most of them are young travelers, including recent university graduates, who have more free time than money.

Economic uncertainties brought by China’s protracted property crisis, weak consumer demand and high youth unemployment rates also means young travelers are more inclined to look for cheap adventures.

“The main reason is budget. Iron butt travel lets me visit more places for less money,” another self-identified “iron butt” traveler, 27-year-old Peng Fei, told CNN.

Many of these travelers still seize rare opportunities to have fun, trying out local delicacies during stopovers and making friends along the way.

But first, they must survive the journey.

Feeling ‘wiped out’

Traveling on overnight buses is pretty standard for backpackers around the world, but their Chinese counterparts have taken the challenge to another level.

For Lin’s trip to Astana, the journey began at 6am from a bus station in Xinjiang. Minus a few intermittent breaks, he spent a total of 46 hours on the bus.

Every few hours, he had the luxury of stretching his legs when the driver pulled over for him and other passengers to get food.

On top of that, he spent most of the trip sitting with his back straight up.

An inside look at the bus Lin spent multiple days traveling on to get to Kazakhstan.

“I couldn’t sleep at all because of my back pain, so I just stayed up all night,” he said in his Xiaohongshu video. “By the next morning, I was totally wiped out.”

“Every minute after that was torture. I wanted to get there early — even more desperate than the driver!” he recalled.

Towards the end of the trip, he also developed a cold.

The sitting was so intense that he felt like it was as exhausting as standing. “When I stepped off the bus, it felt like I’d been standing my whole life and just sat down,” he said.

But that doesn’t mean he and his fellow “iron butt” travelers have to compromise the fun.

A “down-to-earth” experience

Lin likes how “down to earth” the experience can be compared to flying, he told CNN. In the Chinese sense, “down to earth” means having a local touch.

“A lot of people choose the bus because it’s cheap and many are going to work or visiting family,” he said.

“I came across so many interesting stories along the way – about culture, family, or making a living – it’s all super engaging,” added Lin, who has been on 10 iron butt trips since the end of last year, clocking more than 300 hours on buses and trains.

Lin spent 20 hours traveling from China to Laos.

One of his most memorable was a 20-hour bus ride from the southwestern Chinese city of Kunming to Huay Xai in Laos.

When he arrived at the bus terminus, he met a bunch of migrant workers heading to the Golden Triangle, an infamous drug trafficking hub where the borders of Thailand, Laos and Myanmar converge. Many told him they were looking for work there because they felt they had no other choice.

“I asked them whether they were scared. But they said they had a family to feed, a child to feed,” he recalled. “And my heart sank a little.”

Most of these buses and trains routes – particularly those within China – have another intended purpose. They provide cheap options for workers in megacities like Beijing and Shanghai to visit families back in their hometowns.

Many of those people do not choose to travel this way because of a desire to follow a trend. They simply do it because they cannot afford flights or high-speed rail tickets. They opt for affordable alternatives at the expense of spending more time on the road despite having few annual holidays.

Now, though, iron butt travelers are redefining – or perhaps gentrifying – this form of travel.

The view of the Northern Tibetan Grassland during Lin En's train ride to Lhasa, the capital of the Tibet Autonomous Region in China.

During a 53-hour train trip from Guangzhou to Lhasa earlier this year, Lin saw the sprawling Tibetan Plateau, vast Gobi Desert and majestic mountain ranges up close.

“You get to see so much more on the road – stuff you just can’t see from a plane,” he said.

A chance to meet like-minded people

Peng Fei recently spent 10,000 yuan ($1400) to travel to seven countries stretching from Central Asia to Europe.

She went from Kazakhstan to Turkey mostly by bus, stopping in Armenia and Georgia along the way. The only flight she took was from Uzbekistan to the United Arab Emirates, which cost just 300 yuan ($42).

The train Lin takes from southern Guangzhou to Lhasa, the capital of the Tibet Autonomous Region.

Her previous job as a digital marketer was so mundane that she decided to give up her decent monthly salary in an effort to find new meaning through hopping on memorable trips.

During these journeys, travelers spend tens of hours sitting cheek by jowl. Chatting becomes the most natural way to kill time and, in these confined compartments, friendship develops and thrives.

Peng said she met many inspiring people. “I’ve met lots of like-minded young people on the road. Many are undergrads on a gap year or recent graduates – both don’t have much money. They’re not rushing to join the workforce or fit into a social mold,” she told CNN from Egypt, where she is now.

“Most of them are eager to explore other possibilities,” she said.

They also inspire her to seize the days as she doubts whether she could maintain her iron butt when she grows older.

“I want to see as much of the world as I can when I’m young.”