Blue ice caves

The natural wonders of an electromagnetic universe. Blue ice caves due to absorption of electromagnetic light.

Caves and similar ice formations can be created wherever liquid water flows through the ice. The astonishing shapes that result vary every year. Subsurface streams eventually hollow out an interior space, sometimes forming spherical or even egg-shaped areas. If rays of sunlight penetrate the cave's ceiling, amazing blue colors are produced by the natural illumination. The ceiling ice, though thin enough to allow sunlight in, is sufficiently thick to absorb the longer wavelength red and yellow colors. The icy beauty is indescribable.
Ice Cave Beauty | Universities Space Research Association