A 150-foot-long (45-meter-long) light shaft illuminates Grottes de Lastourville in Gabon in a picture released in April 2009.
An expedition team that explored the cave system last summer never discovered the above-ground entrance in the rainforest. But the cavers did explore a total of 14 caves and were able to map 11 of them. The team charted a total of 3.4 miles (5.5 kilometers) of cave--"a large geographical addition to Central Africa," said National Geographic Society Young Explorers grantee and expedition leader Trevor Frost.
Frost and his team hope to help build a case for making the cave system a protected UNESCO World Heritage site.