By Michael Juhran/DPA
San Jose, Costa Rica: The seven women, clad in helmets and climbing harnesses, stand uneasily atop a 10-metre-high metal platform in the canopy of a Costa Rican cloud forest.
A hole in the tangle of forest greenery reveals a deep gorge with two steel cables strung taut above it.
The Rincon de la Vieja volcano isn't far away; moss and ferns, bromeliads and orchids grow on the branches of the trees and the silence is broken only by the twittering of birds.
Until the guide, Jose, speaks: "It's quite simple. You just let yourselves roll, enjoy the view and brake with the leather gloves just before you get to the end."
Kathrin goes first, clipping onto the pulley on the first zip wire and the metal safety clip on the second.
And then she's off, the gorge opening out under her, and the forest all around.
This section of the tour is 400 metres long. Around halfway along, a stream comes into view in the valley below. Adrenaline begins pumping through your body as you go faster and you begin to feel almost weightless.
Screams of delight ring through the forest.
It only takes a few seconds to traverse the gorge but it's an experience that stays with you.
Gradually the whole group arrives at the next landing stage, a fig tree, and everyone's raring to get going on the second leg.
"I could do it the whole day long," says Kathrin, no trace of fear left.
After sailing down 10 sections of zip wire, this part of the tour ends with the "Tarzan swing," a 13-metre-long rope on which the visitors can swing back and forth between the tree tops, just like Tarzan and Jane.
Then the group continues over a series of rope bridges. This time everyone has to be quiet so as not to scare away the wildlife.
Birds and brightly coloured butterflies are everywhere; iridescent toucans, cawing macaws and black turkeys. At home in their natural environment, they appear unfazed by the visitors.
Leafcutter ants, the forest's workers, run busily up and down the tree trunks.
"There are around 100 canopy tours for tourists aged between seven and 70 in Costa Rica," says Jose.
"Between World War II and the 1980s, farmers cut down a third of the forests in our country to make room for grazing for cattle, but now they recognise that the forests are a natural resource which offer hundreds of thousands of species of animals and plants a home and attract tourists," he adds.
Part of the revenues from tourists are poured back into reforestation programmes and around a quarter of the land in Costa Rica is now protected.