Climbers tackle the Gouffre Berger in south-eastern France

1. Climbers tackle the Gouffre Berger limestone cave in south-eastern France, which was once thought to be the deepest cave in the world at 3,680-feet deep (about two-thirds of a mile). It is now ranked the 28th deepest cave in the world.

Climbers tackle the Gouffre Berger in south-eastern France

2. Named after the man who discovered it in 1953, Frenchman Joseph Berger, the cave was once feared as a killer cave where all but the most daring feared to tread.

Climbers tackle the Gouffre Berger in south-eastern France

3. British photographer Robbie Shone said: “This cave used to be considered dangerous but is now far more accessible to cavers.

Climbers tackle the Gouffre Berger in south-eastern France

4. “There are sheer drops to descend,” said Robbie. “as well as passages flooded with water. Once the bottom is reached there’s a real sense of being someone very deep underground.

Climbers tackle the Gouffre Berger in south-eastern France

5. “There are the initials of the original explorers in the last flooded cavern. That’s the end for dry cavers – those who don’t cave dive underwater.

Climbers tackle the Gouffre Berger in south-eastern France

6. The cave has a rich history of British achievement with the world record for the deepest cave dive going to British diver Peter Watkinson and his team in 1967.

Climbers tackle the Gouffre Berger in south-eastern France

7. The cave is liable to flooding after heavy rainfall, which caused five deaths, including Briton Nicole Dollimore from Oxford in 1996.

Climbers tackle the Gouffre Berger in south-eastern France

8. Matthieu Thomas and Sophie Anne pose for their photograph in the Hall of the Thirteen a few days after Matthieu proposed to her at the bottom of the Gouffre Berger cave

Climbers tackle the Gouffre Berger in south-eastern France

9. A caver stands on The Great Rubble Heap close to Camp 1 in The Gouffre Berger

Climbers tackle the Gouffre Berger in south-eastern France

10. Cavers climb along a short ledge in The Great Gallery of The Gouffre Berger cave

Climbers tackle the Gouffre Berger in south-eastern France