The injured German potholer trapped since last weekend more than 900 metres (3,000ft) beneath the Bavarian Alps in a vast subterranean labyrinth was in search of a "super cave" whose existence has intrigued yet eluded geologists and explorers for decades.
Johann Westhauser, an avid potholer since his youth, was hit by a rock fall in Bavaria's vast Riesending cave complex near Berchtesgaden last Sunday. He suffered what doctors have described as a mild version of the crippling brain injury affecting the Formula One driver Michael Schumacher.
Today, the 52-year-old scientist from Karlsruhe is at the centre of one of the most elaborate rescues in potholing history, as 200 specialists from four countries begin the arduous task of bringing him to the surface. Two doctors reached him on Thursday, and said he was well enough to begin a slow ascent. The process could take a week and success is by no means guaranteed.
Austrian rescuer Norbert Rosenberger told Germany's Sueddeutsche Zeitung newspaper on Friday that the feat would be more difficult than retrieving an injured climber from the summit of Everest. "You can forget comparisons with previous underground rescues," he said.
Riesending translates into English as "giant thing". Its scale and complexity is enormous. So far only 12 miles of its hundreds of tunnels, which plunge to a depth of 3,300 feet, have been mapped. The complex is a maze of blind alleys, waterfalls, chasms and rock chimneys. To move along its damp and often slimy rock-strewn passageways, cavers have to squeeze through water-filled gaps of less than half a metre. Most of the cave system remains unexplored.
"The caves are the last undiscovered continent," Professor Edgar Dachs of Salzburg University, Austria said yesterday. "You can discover new unexplored territory here like Christopher Columbus."
The unexplored territory that Johann Westhauser was in search of when the rock fall concussed him last Sunday was a vast cave that geologists and cavers have been trying to find since the Riesending complex was discovered in 1995.
Professor Dachs and other scientists say the Bavarian cave system is almost certainly linked by an undiscovered "super cave" to another 50 mile-long labyrinth comprised of some 4,000 caves in neighbouring Austria called the Kolowrat cave system. "Nobody knows where the link is. Finding it would be a sensation," Professor Dachs said. "It would provide a wealth of new information about our natural water supplies on which millions of people depend."
During the past week, specialist teams in Riesending have been installing new rope-and-pulley systems. They have restocked the complex's five bivouacs where the injured potholer will be brought to rest and recuperate during his long haul to the surface. A subterranean telephone line has been set up to maintain contact with the surface.
But the task remains daunting. Even the entrance instils fear among uninitiated potholers: it is a 540ft-deep abyss large enough to contain the dome of St Paul's cathedral. Explorers say torchlight is not reflected on any rock walls but just "shines into blackness". To reach the bottom where the real labyrinth begins, they have to abseil by rope and use pulleys to re-ascend.
Westernhauser will be taken up in a stretcher made from flexible netting that will enable his body to pass through the narrowest rock gaps. If all goes well his rescuers expect him to reach the surface by the middle of this week. But rainfall could bring the operation to a halt. "Heavy rain turns many of the passages into boiling torrents," said one rescue worker. "If that happens we will have to wait until the water levels subside."