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Welcome to the Marble Cathedral - a natural wonder that could be the world's most beautiful cave network.
An azure temple created by nature, the walls of this network of water-filled marble caverns show just how magnificent the precious geography of our planet can be.
Visitors to the water-sculpted blue caverns see light reflected off the turquoise waters of South America's second largest freshwater lake, General Carrera in Patagonia, Chile.
Light bounces into the caverns and strikes the carved marble walls, creating this enchanting lightshow.
The incredible set of pictures has been captured by landscape photographer and environmentalist, Linde Waidehofer, 67, from Colorado, USA.
'It is the water that formed the unique shapes of the marble walls,' explained Ms Waidehofer in her book on the caverns, Blue Light.
'Originally great ice-fields blocked the western end of the lake - today its glacier-fed waters drain into the Pacific Ocean.
'Geologists have a simple explanation for the breath-taking blue of this giant lake.
'They talk of finely ground glacial silt which makes the water an unearthly blue and crystal clear.
'These waters are magic.'
reach this remote place located in the far southern tip of Chile visitors must fly from the capital, Santiago, 800 miles to the next nearest large city, Coyhaique, and then drive on challenging dirt roads 200 miles south to the lake.
Yet photography students have travelled the world to learn from Ms Waidehofer about light in what could be the world's most astonishing classroom.
'Since 2003 I have taken many photography students into the caverns and it is always the highlight of their South American voyage,' Ms Waidehofer said.
'The experience is always different because both the light and the water level of the lake are continually changing.
'The water itself can vary from turquoise to deep blue depending on the weather and the time of year.
'In early spring the water of the lake is at its lowest point because the surrounding glaciers have not yet started to melt.
'So the light will be reflected in a totally different way than later in the year after the melting glaciers have raised the water level over a metre.
'This changes what the visitor will see from the small boats needed to access these mysterious formations.'
The rivers that feed into the lake are in danger of being over-developed if the Chilean government gives the go-ahead to building projects.
Ms Waidehofer feels strongly that this natural treasure needs to be protected so future generations can also experience its wonders.
'Patagonia's rivers including the beautiful rio Baker that flows from this lake are in danger of being developed into a system of dams if the Chilean government gives the go-ahead,' she said.
'Even though the marble caverns of Lago Carrera have been named an official nature sanctuary by the Chilean government, they are not safe from the impact of these projects.
'Enormous high-tension power lines could be constructed along the shore just above the Marble Cathedral.'
Since falling in love with the Marble Cathedral during her first visit in 2003 she has decided to make it a major part of her life.
'I love it so much I've visited the marble caverns dozens of times,' she said. 'I don't know anything quite like them anywhere.
'I was so crazy about visiting that I decided to buy land, build a house and spend half the year here. My new home sits above two marble caves and even the floors are cut out of pure marble.
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