The entrance to the cave complex lies more than 6,000 feet up in the Bavarian Alps, and can usually only be reached by a gruelling climb. A helicopter is making ten trips a day just to ferry supplies in: at first it had to lower rescuers on a rope, but now a landing area has been cleared. Storms are forecast, and if they make it impossible for the helicopter to fly, the Bavarian Mountain Rescue service says it will use pack mules.