They have discovered an "underground Everest" in the Peak District plunging to 500 feet - some 135 feet higher than the Gaping Ghyll in Yorkshire, regarded for as long as anyone can remember as Britain's deepest cave.
Dave Nixon, 31, a rope access technician, was one of the 12 cavers who had to tunnel their way through 100 feet of rock.
"If you told me five months ago that we would find a shaft of this size at all, I would not have believed you," he said. "There are not many places left that no one knows anything about. I have dedicated a big part of my life to it and sacrificed a lot so I am feeling quite happy with myself."
Mr Nixon and his friends have christened the cave Titan. The cavers suspect there could be even bigger caves in the area awaiting discovery.
They tunnelled their way through to Titan from Peak Cavern at Castleton. Its shaft is so high it took six months to climb to the top. "It's amazing to think you can do this 20 miles from the middle of Sheffield," said Mr Nixon.
Experts knew the cave existed but had no idea of its size. It was thought that access could be obtained only by swimming through pitch-dark flooded tunnels. After seven years of searching for for a safe dry route, Mr Nixon and his team found themselves in Titan and began their six-month climb.
Throughout the exploration they were in great danger. A wrong move and the wedged boulders would have crashed down and crushed them. At one stage they even laid a tiny underground railway to help to move the rocks and rubble along the tunnel.
Titan was a completely unexpected find. "It all happened in a couple of days," said Mr Nixon. "We got to a situation where we were standing at the bottom of this bloody great hole and we couldn't see the top of it."
They began climbing the limestone walls of the shaft using ropes and bolts to inch their way up to the roof. As they climbed, the enormity of their discovery became apparent.
Dave Arveschoug, 48, Derbyshire correspondent for Caves and Caving, part of the British Cave Research Association, and one of the cavers, said: "It's the biggest find since sliced bread in caving terms. It's extremely significant as it was thought there was never going to be anything higher than Gaping Ghyll. It's spectacular and frightening, and even hardened cavers are intimidated by its height."Reuse content