In Bolivia's jungles and steep cliffs the Yungas people do not walk. They fly on ropes like birds - faster than astronauts.

These 'birds' are known as cocaleros, or coca harvesters. They use ropes to swing across the narrow valleys, suspended from ancient rusting pulleys.

It takes all of 30 seconds from one side to the other. By foot it would take more than an hour.

"This must be about six or seven years old. Before then there was nothing. Nothing," Synthe, a harvester, says. "We had to walk down to the bottom, cross the river and then climb up the other side. It used to be quite a hike."

The Yungas Valleys are like a sudden staircase between the towering cordilleras of the Andes - more than 4,000 metres high - and the green Amazon basin.

The vertical landscape is dramatic. The inhabitants have fashioned this unusual way to move around quickly, with simple, thin wires normally used for fencing stretching as far across as 400 metres.

It is almost a form of public transport. There are about 20 of these cables strung across the valley. All day long, people and goods fly across the river 200 metres below.

At each end the homemade tethers theoretically provide stability and safety. Some of the wires have been in use for 20 years, and have slackened dramatically.

The cocaleros have never bothered replacing them. One of them explains: "It doesn't break. It will never break. It's galvanised steel and anyway we've put four of them across here."

Flying high

At 72, Don Ignacio continues to fly across the valley every day to tend to his coca plantation on the other side of the mountain.

Since the price of coffee collapsed, coca has taken over as the main crop for the Yungas. It has been cultivated since the time of the Incas, a form of narcotic chewed by the locals to overcome tiredness. It is harvested three times a year and is worth approximately 30 per cent more than coffee.

Don Ignacio was the first to settle in the valley and it was his idea to install the cable skyway.

"I first came here in 1955. I was the one who founded the community and everything you see here. There was nothing before, nothing to get across. We used to carry everything on our backs, just like pack animals. That's when I thought about having the system of pulleys and cables. I bought steel wires and I managed to stretch them across the valley using rope," he says.

Don Ignacio's invention changed the lives of the cocaleros. Now they can easily send heavy loads across the valley. But there are some who still doubt the flimsy wires that crisscross the valley.

Maria's husband was killed in an accident on the wires and she now refuses to use them, despite the physical exertion of the steep climb.

"My husband fell off and fell to his death into the river. He lost his balance somehow, fell out of his harness and fell. I'm not sure what really happened, but he was on his own when he fell," she says.

In the past 20 years, three people have fallen to their deaths, mostly due to negligence. Like Maria, most women prefer to cross on foot.

"This bridge is for the women. We're too scared to cross on the cables, so most of the women cross here. It's quite nice because we often stop to bathe in the river.

In the Yungas Valley the work days are long and arduous. The hardest is the harvesting of mandarins, which grow in abundance but have to be picked within two days of ripening, otherwise they rot.

Maria and her new partner Alex can only sell fresh mandarins at the market. So, timing is crucial.

"It's always a rush, and that's when you might have an accident from hurrying so much you might get careless and fall," says Alex. "That's why the cables aren't as reliable as they say ... it's like Russian roulette."

Road of death

Life for Bolivia's cocaleros, such as Severo, has improved a little since Evo Morales became president in 2005. Morales was the first native Indian head of state in South America and an outspoken advocate of coca farmers. He relaxed legal restrictions imposed previously on coca growing.

"Before, there were embargoes and serious restrictions. Earlier governments had said they wanted to stop coca altogether. No one listened to our side of the story," Severo explains.

"'Coca is used to make cocaine' they said, but it's not true. Coca is not cocaine. You need to add a lot of chemicals to make cocaine from coca leaves."

And, Severo has never even seen cocaine. To him, coca is a powerful therapy against fatigue, pain and altitude sickness.

Severo must make a five-hour bus ride to the Villa Fatima market in La Paz, the only place in Bolivia where the cocaleros are allowed to sell their crop.

Despite efforts to control the sale of coca leaves, an estimated one-third of all that is sold here end up in the laboratories of cocaine traffickers. And, it is almost impossible to monitor unless enforcers trail all the vehicles that leave the market filled to the brim with coca leaves.

But first, he needs to drag the packed coca leaves to the nearest road on the other side of the Yungas Valley. It is a back-breaking 10 minutes up the mountain.

The road snaking its way through the valley of cables is the main artery that links the mountain range with the plains 4,000 metres below - a narrow dirt track as busy as any modern highway.

Bolivians call this road 'el Camino de la Muerte', or the road of death.

On the way down are manufactured goods from La Paz; on the way up are rice, fruit and cattle from the fertile Amazonian pastures. Two-way traffic causes vehicles to teeter on the edge of precipices.

Severo sells all three of the 25kg bags of coca leaves for 700 Bolivianos, or $180. The money he makes from the sale will get him household supplies and some cash for his wife.

After spending a couple of days with his family, Severo heads back to the valley. Back with Don Ignacio. Among the flying men of the Yungas and their coca fields along the road of death.

Source: Al Jazeera