The tubes' story begins 190,000 years ago in Australia, where a young volcano named Undara was burbling up enormous volumes of molten lava onto the gently sloping plains of northern Queensland. It flowed at temperatures of 1,220° C across 1,550 square kilometers of land, creating the earth's longest flow of lava from a single volcano. Researchers estimate that Undara's geological cocktail spewed forth at about 1,000 cubic meters per second – enough to fill 1,500 semitrailer-sized tankers every minute.
An estimated 23 billion cubic meters of lava flowed across the landscape, reshaping it into new geological forms as it cooled and hardened. Lava tubes form when the lava on the outside of a flow, exposed to air and earth, cools faster than the inside. As the still-molten rock inside flows out, it leaves tunnels and caverns in its wake. One such lava tube is over one hundred kilometers long.
In the 190,000 years since they were formed, the lava tunnels have become home to diverse array of strange animal life. Vines and plant life have invaded through holes in tube ceiling, and all-white cockroaches and Scutigerids (think giant silverfish) skitter about beneath one's feet. Thousands of specialized cave bats, snakes which eat the bats, frogs which emerge only once every few years during a very rainy season, and other bizarre life forms have all adapted to the long and often hidden lava tunnels.
It is likely that there are many other endemic life forms living in the cave system. The longest tunnel, Bayliss, contains up to 200 times the ambient atmospheric level of carbon dioxide and is difficult to explore, creating the perfect environment for adaptable creatures to take hold.
There was little interest in the caves until the 1970s, when NASA began to explore them as potential models for the moon's geology. Today they are visited by over thousands of people a year, and tours are offered daily.