Caves

 It is fascinating to see how water and rock have developed vast subterranean highways and dissolved underground rooms that range from chest squeezing passageways to massive stadium sized Colosseum's full of formations.  Caves also act as geological time capsules by preserving some of the most amazing clues to our planets pastime and venturing into these underground worlds can not only be a journey into our planets past but can also hold clues to some of the most amazing anomalies that have made this planet such a beautiful place.