Each year, thousands of people journey to New Mexico to see Carlsbad Caverns, the largest caverns on earth.
These huge underground caves were formed by water dripping from the ground through layers of rock salt and limestone, dissolving the rock and hollowing out the caves. The caverns may be close to five million years old!
The total area of the caverns is unknown. So far, they have been explored to a depth of about 1,000 feet. The largest single cavern at Carlsbad, called the Big Room, is 1,800 feet long, and its arching ceiling is 255 feet high at some points. Altogether, the Big Room covers 14 acres!
In summer, bats that live in part of the cave emerge each evening to begin hunting for insects. When insects are plentiful around Carlsbad, the number of bats living in the caverns can be close to a million!