Java, Indonesia
Best observed under the light of the stars, few sights invoke such other-worldly awe as Kawah Ijen, a volcano where dazzling, neon-blue flames can be seen erupting from cracks in the Earth. The stunning sight is a result of sulfuric gases igniting upon release, at which point columns of fire reaching up to 16 feet appear to spell-binding effect; and if that wasn’t enough, further on you will encounter the world’s largest highly acidic lake, a one kilometer caldera filled with water so acidic it has turned green. When combined with the pitch black darkness that envelopes you, this truly once in a lifetime experience evokes feelings that border on the indescribable.
