Zakynthos (Greece) (AFP) - When he was nine, Michal Trzajna jumped off a second-floor balcony at the prompting of his brother -- and broke both his legs.
Thirteen years later, he still can't explain what drives him to leap from 200-metre (650-foot) cliffs at the end of a rope.
"I used to live near an airport, and dreamt of jumping from planes," the 22-year-old tells AFP.
"When you succeed in controlling your body in mid-air, the sensation is simply unique," he says.
Michal is one of a group who have travelled from Poland to the island of Zakynthos, one of Greece's most renowned leisure spots -- but not to lie in the sun.
On this bright summer day, he is perched high atop the rugged rocks overlooking the azure waters of Navagio beach.
In a flash, he disappears and moments later, a clamour goes up from the beach below as his body arrows towards the bathers.
Metres from the ground, it's almost unreal how Michal's fall breaks, turning instead into a smooth balancing act.
This is rope jumping -- part diving, part rock climbing, with a touch of engineering.
"This is 100-percent recommended," says Marta Jamenes, a jumper from Spain.
"When you jump you learn how to control your body in the air and it is something like learning to swim, it's the same. You get your body used to free-fall," she says.
The discipline is similar to bungee jumping, only the criss-cross rope ensemble stretching from the rocks to the harness on the athlete's back is much more elaborate.
"The advantage over bungee jumping is that here, 80 percent of the jump is free-fall," says Michal. "In contrast, the elastic rope (in bungee jumping) limits the fall to 35-40 percent of the height."
"The rope is not attached to a platform, as in bungee jumping, but to other ropes horizontally stretched across the cliff," explains Michal's companion Lukas Michul, a former paramedic, as he prepares to hoist his friend for another jump.
"When you jump for a first time at a new location, your heart beats wildly, your legs tremble, adrenaline flows. Pleasure comes gradually with each jump," he says.
- Precision jumping -
It's all about precision, a calculation of weight and height down to the last millimetre to keep the ropes taut.
"We have to be aware how to control our body while falling, how to use the wind, how to use our legs and arms," says Michal.
If done properly, there is no risk, the two jumpers insist. The installation -- which can take 10 days to set up -- can be applied equally to mountains, cliffs and skyscrapers.
"It's very safe, because of the ropes that are here are very reliable and there has never been any accident with them, so far, in the whole world," says Michal.
Born in the '90s, free-fall jumping from bridges and platforms has a wide appeal -- but only a few squads around the world try their hand at this extreme version.
"There are groups of Russians, Ukrainians, Spaniards, Lithuanians, Frenchmen -- and then there's us," says Lukas.
The Polish team is named "Dream Jump", and with reason, says 37-year-old squad leader Thomas Zielinski, a former high-altitude worker.
"The project... will primarily take us in 80 places around the world. We want to travel to the most beautiful places in the world you can possibly jump from," he tells AFP.
The island of Zakynthos was their third destination this year, after the Verdon Gorge in southern France and Kjerag mountain in Norway.
Next up on their programme: leaps at a cave complex in Croatia, a French viaduct, skyscrapers in Las Vegas and Johannesburg, and from the rim of the Grand Canyon.
"We want to share with the world how safe and beautiful this sport is," says Lukas.
"That's why we just want to go around the world to show that this is so nice and so unique and everyone can try."