Explore underground caves: Kartchner, Luray, Mammoth, Carlsbad and Castleguard

What lies beneath can be cold, damp and compelling. Learn about dry and wet caves, the creatures that live in them and the characteristics that create these natural settings. Here are five places to explore underground:

Kartchner Caverns, Benson, Ariz.

In 1974, two University of Arizona students and amateur cavers spotted a narrow crack in the bottom of a sinkhole. They followed the unusually moist air and discovered more than two miles of unspoiled cave passages. The caverns, carved from limestone, were not opened to the public until 1999 and are part of the Arizona State Park system. Visit this living or "wet" cave, to experience stalactites, stalagmites, "cave bacon" and small white helictites. Many of the resident minerals are not found in any other cave in the world. Among the cave's highlights: a 22-foot-long "soda straw" stalactite, reported to be the second longest in the world. For a unique experience, visitors ten and older can experience the cave as the first discoverers did during a tour that uses only light provided by a helmet headlamp.

MORE INFO azstateparks.com/parks/KACA/

Luray Caverns, Luray, Va.

On a summer day in 1878, the local tinsmith and several adventuresome friends were exploring the countryside in search of a cave. What they found is now one of the most widely visited cavern systems in the eastern half of the U.S. It is perhaps most well-known for its Great Stalacpipe Organ, a lithophone that produces tones similar to musical instruments and is considered the largest musical instrument in the world. Visitors can tour cathedral-size rooms and see towering stone formations from a paved walking path. Check out several on-site museums, including Toy Junction, which is popular with the junior set.

MORE INFO luraycaverns.com

Mammoth Cave National Park, Mammoth Cave, Ky.

This National Park in the hill country of south central Kentucky preserves the world's largest known cave system and is a designated UNESCO World Heritage site. Explore 400 miles of vast chambers and complex labyrinths on a variety of tours designed to appeal to multiple ages and abilities. If you are not sure spelunking is for you and your family, consider the short, small-group Introduction to Caving tour. Later enjoy camping and canoeing along the scenic Green River. Reservations are strongly recommended.

MORE INFO nps.gov/maca

Carlsbad Caverns National Park, Carlsbad, N.M.

Underneath the magnificent desert landscape of southeastern New Mexico and West Texas are more than 300 known caves. Visitors to the park, two-thirds of which is a designated wilderness area, can inspect more than 100, including some of the largest caves in North America. The 8.2-acre Big Room is partially wheelchair accessible. The Queen's Chamber is considered the most beautiful and scenic. Self-guided and guided tours are available and timed entry tickets are required.

MORE INFO nps.gov/cave

Castleguard Cave, Banff, Alberta, Canada

This remote underground marvel is known for its nest of extremely rare cubic cave pearls and an extensive array of flagged "soda straw" stalactites. Experienced explorers can stay in the cave at one of two underground camping sites within Banff National Park and study the unique plugs of glacial ice pushed into the cave from the sole of a surface ice field. Permits are required.

MORE INFO pc.gc.ca/en/pn-np/ab/banff