The deep blue Crystal Cave of Svmnafellsjvkull (CORR) in Skaftafell, Iceland was created by the glacier from Vrffajvkull Volcano's icecap meeting the coastline. The deep blue color is due to centuries of compression removing air from the ice.
Fingal’s Cave, Inner Hebrides, Scotland. "Fingal's Cave is a sea cave on the uninhabited island of Staffa, in the Inner Hebrides of Scotland, part of a National Nature Reserve owned by the National Trust for Scotland" via Wikipedia.
In pictures: Inside Hang Son Doong, the world's largest caves in Vietnam
The Marble Caves is geological formation of unusual beauty. These caves have formed in a pure marble and are bathed in the deep blue water of General Carrera Lake. Chile, the Marble Caves are some of the most impressive attractions of Patagonia.
The pink and lovely. Hiller Lake (Western Australia) Its startling color remains a mystery and while scientists have proven it’s not due to the presence of algae, unlike the other salt lakes down under, they still can’t explain why it’s pink.
Explore the ancient caves of Hang Son Doong, Vietnam. Hang Son Doong is one of the largest caves in the world and features a fast-flowing underground river. For spelunkers, exploring Hang Son Doong is the equivalent of scaling Mount Everest.