formation called hymir's castle in an ice cave "eisriesenwelten" in the alps near salzburg

alps salzburg giants ice eisriesenwelten chill chilly freeze freezing speleology underground tourists tennengebirge mountain cave hochkogel inside werfen limestone natural austria stalagmite stalagtite tunnel carving geology caving exploring explorer darkness formation eisriesenwelt german for world giants1 located about south section largest extending more than visited 200 000 every year called hymir's castle near