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Awash with kaleidoscopic colours and crystal blue ice as far as the eye an see, these are some of the largest natural ice cave formations in the world.
Taken mostly by intrepid photographers whove ventured far and wide to explore their depths, these stunning pictures look like scenes from the make-believe kingdom of Disney hit Frozen.
But at a time when global warming threatens our natural landscape, saviour them while you can, as they might not be around for much longer.
1. Vatnajokull Glacier, Iceland