They call it the Marble Cathedral, a network of water-filled marble caverns in South America's second largest freshwater lake, Lago Carrera. Ice fields once blocked the western end of the lake but now the the glacier-fed waters drain into the Pacific Ocean where Chile and Patagonia end.
Geologists believe the colour and clarity of the lake is due to finely ground glacial silt. The water level is constantly changing and the photography is never the same because of the filtering light.
The water can vary from turquoise to deep blue depending on the weather and the time of the year.
But just because it's so beautiful doesn't mean it's safe. Patagonia's Baker River which flows from this lake is part of a dam system that Chile wants to develop even though this area has been named an official nature sanctuary.
If you want to read more about these beautiful caverns then information about Linde's book "Blue Light" can be found at http://www.westoneye.com/books