Esa'ala Cave

Papua New Guine

Esa'ala Cave is located in located in Papua New Guinea. The elliptical mouth, on a slope of karst, is 49 by 62 m wide and is undercut around all its perimeter, further widening to a room approximately 303 by 135 meters (994 by 442 ft) wide. The floor of the cave is a 333 meter (1092 ft) free fall drop from the lowest side of the opening, with a 370 meter (1,214 ft) drop from the highest side, making it the largest known cave shaft in the world. 

Opened up by water erosion in a fault on an impermeable limestone plain and with a roughly conical shape, the cave has been known to the local people since ancient times.

Temperatures in the cave are low. Vegetation grows thickly at the mouth, where rains can cause waterfalls cascading into the cave. The cave floor is covered with a thick layer of debris and guano on which "millipedes, insects, snakes, and scorpions" live. There is also a narrow sinkhole in a fault of lower createceous limestone which goes down at least a further 512 m.