While you may not know it -- America has as much to see underground as it does above ground. The abundance of caves in nearly every corner of the country means exploring is never too far away. With a knack for finding natural beauty and a sense of smallness in the universe, spelunkers need nothing more than a good pair of shoes to find an adventure.

Here are five of the best places to go caving:

Caverns of Sonora, Texas

New crystals are still forming in much of this vast complex in Texas, making it one of the most actively growing caves in the world. It’s filled with loads of sparkling mineral formations from coral trees to stalactites. Adventure-seekers can also get up close and personal on the “Discovery Challenge,” where you will rappel 50 feet down into the Devil’s Pit.

Photo Credit: Clarkmaxwell

Mammoth Cave, Kentucky

If you’re going to explore caves, why not hit the world’s longest? With 390 miles traversed to date and “no end in sight,” the Mammoth Cave certainly lives up to it's name. The national park system hosts a number of affordable tour options that offer a glimpse of the Frozen Niagara formations, lantern-lit passages, underground rivers, lakes, canyons, and limestone walls.

Photo Credit: Tjflex2

Oregon Caves National Monument, Oregon

Tired of being baby-sat on the no-touch guided tours? Oregon Caves National Monument offers an off-trail caving tour, that includes a guide but also instruction on technique and etiquette. Best of all, the three-hour tour means you get to climb and crawl around the marble surfaces as much as you want, wherever you want for a truly personalized spelunking experience.

Photo Credit: Sathish J

Carlsbad Caverns, New Mexico

Fossils of plants and animals left from the ocean are trapped within the walls of these historic caves and a visit to the grand “Big Room,” is a must. With paved walkways, handrails and lights, it’s one of the most modernized caving experiences in existence and offers both tours and self-guided viewings.

Photo Credit: Gene

Lehman Caves, Nevada

It’s not the biggest or the baddest cave system, but the Lehman Caves in Nevada are arguably the most beautiful, with more than 300 rock formations made of marble. It’s extremely fragile, so most outside items are not allowed and it’s accessible by one of three tours only.