"I sneaked into the Torre de Cristal in Madrid with my colleague Manuel Chana and we jumped from the 249-meter tower, Spain's highest building, in January 2008," says "El Amarillo," an Austrian based in Spain who prefers only to reveal the initials of his real name: H. S. His friend Chana has since died in a parachuting accident.
"We dressed in overalls and pretended be workmen," he explains. "We sneaked in at lunchtime and went up to the top floor. We had to climb up the last few meters. Just before we jumped, we took off the overalls and put on the parachute.
"Jumping off the Torre de Cristal was something incredible, because we knew what we were doing was illegal. It was an enormous rush, one that I will never forget," he recalls.
BASE jumping is a form of parachuting that takes its name from the initials of the four kinds of location from which practitioners can launch themselves: buildings, antennas, spans (bridges) and earth (cliffs). You can view an array of their exploits, featuring jumpers such as Armando del Rey, Abraham Cubo, Álvaro Bultó, Santiago Corella and Toni López, Daniel Hernán and El Amarillo, on the internet, on sites such as YouTube. In urban areas the jumps are usually illegal, as the owners of Spain's major buildings are reluctant to allow such jumps, which are highly dangerous.
We knew what we were doing was illegal. It was an enormous rush, one that I will never forget"
"I have seen four people die right next to me," says Hernán, who works as a parachuting instructor and a fireman. "And some of them were friends, which is why I am conscious of how dangerous all of this is."
He says he took up the sport almost by chance: "A friend bought a suit and we went to the mountains to try it out. Now I think it was madness, but it all turned out OK."
The people who die jumping off buildings fit two different profiles, he believes. "They can either be experts or novices; the first because they are over-confident, the second because they don't know how to react to a problem."
The records broken by El Amarillo's fellow countryman Felix Baumgartner last month, when he jumped from over 39,000 meters and broke the sound barrier with a speed of 1,342.8 kilometers per hour, have made the activity better known. Even so, there are barely more than 30 BASE jumpers in Spain.
"I met Felix in California and I remember he was already making a name for himself then, as he jumped out of a plane dressed as a cowboy, with boots on and everything," says El Amarillo.
Hernán acknowledges Baumgartner's achievement. "It is something any of us would have dreamed about. I got to know about his exploits a while ago, like when he sneaked into the Taipei 101 towers [the world's second-tallest skyscraper] in Taiwan."
BASE jumpers use suits with wings that allow them to glide much further: "We manage to travel four meters lengthways for every meter that we fall," explains Hernán. "And that is almost like flying."
He says the risk increases depending on the jumper's proximity to the wall from which they launch. "The adrenalin explodes through your body, and that's why it is much more difficult," explains the instructor, who says he would never dream of teaching BASE jumping. "I don't want anyone's death to be my responsibility."