This is the crystal cave of giants found in the Naica Mine, Chihuahua, Mexico. These are Selenite crystals (gypsum) and are the largest crystals ever discovered... They are 1000 feet down in a limestone host rock, where they are mining for lead, zinc and silver.
Blue Magic on Biševo (Croatia). 'Of the numerous caves around the remote limestone island of Biševo, the Blue Grotto (Modra Špilja) is the most spectacular. On a clear morning, the sun’s rays penetrate through an underwater hole in this coastal cave, bathing the interior in a mesmerising silvery-blue light.