Surveyed length685,000 m
1.9 trillionthsOrion Nebula diameters
85,625Sailboat lengths
2.7 millionTambourine diameters
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Longest Cave System
Mammoth Cave stretches over 685 km underground, and new passages are still being found/Collective & Conceptual
Mammoth Cave in Kentucky, USA, is the longest known cave system in the world, with over 685 km (426 miles) of surveyed passages as of 2024. This is more than twice the length of the second-longest cave (Jewel Cave in South Dakota at about 346 km). Despite centuries of exploration, new passages continue to be discovered, and some speleologists estimate the total length could exceed 1,600 km. The cave was carved over millions of years by slightly acidic groundwater dissolving limestone. It contains five distinct levels of passages at different depths, recording millions of years of geological history. The cave supports a unique ecosystem including eyeless cave fish, cave crickets, and rare cave shrimp.
Measurements
Estimated total length1.6 million m
37.5 millionGolf ball diameters
21.9 millionLipstick tubes
Maximum depth115 m
6,037Penny diameters
11.8Squash court lengths
Park surface area214 million m^2
16.5 millionParking spaces
238Airport runways
23.8 billionPhone screens
About 214 km^2
Formation age315 trillion s
1.4 millionDog years
2.1 trillionPopcorn bags
1.3 septillionProcessor cycles
About 10 million years