Extreme Caves Pictures

Lava Tube

Photograph by Patrick McFeeley

Steam rises from the Pacific as molten lava pours from the fiery interior of a lava tube near Kilauea, Hawaii. Lava tubes are created when lava flows through a channel for long periods of time, gradually building natural levees along its sides that eventually connect into an overlying roof. When lava flows stop, the caves may be left behind for exploration. Kilauea's tubes extend from the ocean to vents on the flank of the Pu'u 'O'o cone.

Ellison's Cave

Photograph by Michael Nichols

Their headlamps dimming in the distance, a group of cavers descends into Ellison's Cave far under Pigeon Mountain in northwest Georgia. The cave's "Fantastic Pit," seen here, is the deepest cave drop in the continental United States at a staggering 586 vertical feet (179 vertical meters).

Krubera Cave

Photograph by Stephen Alvarez

A caver rappels into the first pit of Krubera Cave in the Caucasus Mountains of Abkhazia, a politically disputed breakaway region of Georgia. Krubera is the deepest known cave in the entire world, delving more than 7,188 feet (2,191 meters) underground. Exploring it requires a kind of reverse mountaineering, as teams spend weeks moving from camp to camp while working their way even further into the Earth.

Hand of Dog stalagmite in Hang Son Doong Cave

A spelunker takes a close look at the Hand of Dog stalagmite in Hang Son Doong Cave. The "Mountain River Cave", in a remote part of Vietnam's Annamite Mountains, was first explored in 2009 and boasts caverns large enough to hold a 747 airplane. In fact, though explorers have only scratched the cave's surface it may be the world's largest with continuous passages as wide as 300 feet (91 meters) stretching more than 600 feet (183 meters) high.

Kayaking Through Glacier Caves

Photograph by Doug Demarest

A sea kayaker cruises through a glacier cave carved out from among the giant icebergs of Resurrection Bay near Seward Alaska. Glacier caves are often created by the action of water on ice, though not all end up partially submerged as this iceberg example.

Waitomo Caves on New Zealand's North Island

Photograph by Paul Zahl

Boaters on an underground river enjoy a facsimile of the night sky created by a galaxy of glowworms on the roof of the Waitomo Caves on New Zealand's North Island. The tiny worms have become a rather large tourist attraction, and the caves they call home also boast notable stalactites, stalagmites, and interesting limestone rock formations.

Cave of Crystals in Naica, Mexico

Photograph by Peter Carston

A caver explores an otherworldly landscape in the aptly named Cave of Crystals in Naica, Mexico. The ice-cooled suit isn't just for show, the cave's 90 percent humidity and high temperatures (118 degrees Fahrenheit, 48 degrees Celsius) could kill a person in half an hour. The 36 foot-long (11 meter-long), 55-ton gypsum crystals here formed in hot, mineral-rich water that filled the cave until local mining operations pumped it dry. Should the mine close and pumping cease, the caves will refill and crystal growth will begin again.

"Snotties"

Photograph by Stephen Alvarez

A caver examines single-celled organisms, called "snotties," that produce a prodigious slime with a nasty kick-an acidic level rivaling battery acid. In Tabasco, Mexico's Cueva de Villa Luz these bacteria oxidize sulfur compounds that enter the cave from subterranean springs. Sulfur is the basis of nearly all life forms in this toxic-to-humans environment and cavers wear respirators for protection against sulfurous vapors.

Cave of Swallows

Photograph by Stephen Alvarez

The Chandelier Ballroom

Photograph by Michael Nichols

The Chandelier Ballroom is a spot of extreme beauty, where gypsum crystals up to 20 feet (6 meters) long sprout from the ceiling of Lechuguilla Cave in Carlsbad Caverns, National Park, NM. Lechuguilla, one of the world's premier caves, lies some 1,640 feet (500 meters) below the desert and stretches for some 120 miles (193 kilometers).

Mammoth Cave

Photograph by Stephen Alvarez

Mammoth cave is massive, in fact it's the world's longest known cave system, but cavers must still be prepared to deal with the many tight spots familiar to all who explore underground. Under south central Kentucky the cave's linked honeycomb has been surveyed for more than 360 miles (580 kilometers). Experts believe that its full extent might be more than 1000 miles (1600 kilometers).

Glacier Cave

Photograph by Borge Ousland

A small "glacier cave" on the north polar ice cap offers a frigid refuge and and a wide sampling of exotic ice crystals. While many conventional caves are born from the actions of water and rock they form differently on Arctic's floating pack ice. Large glacier caves here grow where fissures are cut, and subsequently enlarged through the ice sheet, by the actions of seasonal meltwater or geothermal vents.