Remote ice caves appear in a kaleidoscope of colors in these stunning shots. Denis Budkov, 35, trekked inside the dangerous caves - which could collapse at any moment - to capture the colorful scenes. The rainbow caves are given their various colors by light refracting through the ice - with the thicker the ice, the more emerald they appear. And Denis, from Kamchatka, in the Russian Far East, also decided to add his own take - by lighting flares to turn the normally blue hues into dark reds. (Denis Budkov/ Caters News Agency)