This is an ice cave, known as "crystal Cave" on the frozen lagoon of the Svínafellsjökull glacier in Skaftafell, Iceland. This snow, which is up to 1000 years old has metamorphosed into highly pressurized glacier ice that contains almost no air bubbles.
Travel Information: The Hidden Beach - Marieta Islands, Puerto Vallarta, Mexico >>> I would love to take a dip here! We have been to Puerto Vallarta several times but never to this place! Maybe because it is hidden!