Grotto of Casteret
The Grotte Casteret, also known by its Spanish names Gruta de Casteret or Gruta Helada de Casteret, is a limestone ice cave, located high in the Spanish Pyrenees, within the Ordesa y Monte Perdido National Park. Discovered in 1926 by Norbert Casteret, it is known for its Grande Salle (Great Hall) which has a frozen lake some 2,000 square metres (22, 000 sq ft) in area, its ice formations, and a 20 metres (66 ft) ice wall into a second chamber.
Cave data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).