http://timewheel.net/Image-Iceland-s-Crystal-Cave-Is-A-Scene-Of-Pure-Magic

Beneath the Breiðamerkurjökull glacier in Iceland’s Jökulsárlón glacial lagoon, there is an enormous natural cavern of unbelievable beauty. The cave has been delicately sculpted from years of underground lava flow and geothermal heat emissions interacting with the hydrologic cycle, resulting in this breathtaking natural formation.

The ice that forms the walls of the cave is unbelievably dense, having been subjected to centuries of compression and stifling amounts of pressure. As ice involved in this process achieves higher levels of density, it is able to prevent less red and yellow light from the sun to pass through it, giving the cave its soothing blue glow.

http://timewheel.net/Image-Iceland-s-Crystal-Cave-Is-A-Scene-Of-Pure-Magic

Six more photos at above link.