Carls­bad Cav­erns, locat­ed in the Guadalupe Moun­tains in south­ern New Mex­i­co, is anoth­er pop­u­lar U.S. cave sys­tem. Hun­dreds of thou­sands of years of ero­sion have cre­at­ed stun­ning, almost car­­toon-like rock for­ma­tions through­out the cav­erns. The esti­mat­ed 120 lime­stone caves and sur­round­ing 720 acres were des­ig­nat­ed Carls­bad Cav­erns Nation­al Park in 1930, and in 1995, the prop­er­ty was named a UNESCO World Her­itage Site.