Mammoth Cave National Park

01This week on our national parks journey, we head to the southeastern state of Kentucky.

02Here you will find rolling hills and thick green forests.

03But beneath the land is a strange and silent underground world.

04One early explorer described it as grand, gloomy, and peculiar.

05Welcome to Mammoth Cave National Park.

06Mammoth Cave is the longest known cave system in the world.

07It is two times as large as the world's second biggest cave system.

08Its size helped give it its name.

09Mammoth, as an adjective, means extremely large.

10Mammoth Cave National Park is in Kentucky's Green River Valley.

11The park covers over 20,000 hectares.

12It protects the river valley and hilly land, as well as the vast underground cave system.

13The U.S.

14Congress formed Mammoth Cave National Park in 1941.

15Forty years later, it was named a World Heritage Site.

16And in 1990, it became a UNESCO Biosphere Reserve Site.

17Researchers and explorers have mapped more than 600 kilometers of passageways in Mammoth Cave.

18And scientists continue to explore it.

19Water formed the cave over millions of years.

20Other than the Green River, few sources of water exist above ground.

21That is because water seeps quickly into the earth.

22Soil made of broken-down limestone absorbs the water.

23This has created a vast and complex system of chambers and passageways.

24A delicate and unique ecosystem exists inside the cave.

25More than 100 kinds of animals live in Mammoth Cave.

26Some of them live their whole lives in total darkness.

27Mammoth Cave, cave shrimp, and many other kinds of eyeless, colorless species can be found.

28Mammoth Cave was once home to about 10 million bats.

29They included species like Indiana bats, big brown bats, little brown bats, and the eastern small-footed bat.

30Now they number in the thousands.

31Humans first entered Mammoth Cave about 4,000 years ago.

32They discovered uses for minerals inside the cave.

33Researchers described them as primitive miners.

34Humans explored Mammoth Cave for nearly 2,000 years.

35Then their exploration appears to have ended.

36Many stories name John Houchins for rediscovering the cave.

37They say he was hunting in the area when he came upon a black bear.

38The bear was close to the entrance of the cave.

39Houchins shot the bear, but he failed to kill it.

40The bear ran, and Houchins followed.

41It led him into the cave.

42Experts do not agree on the exact year of Houchins' discovery, and some people questioned the story entirely.

43Slaves played many important roles at Mammoth Cave during the 1800s.

44During the War of 1812, slaves mined the cave for a mineral called saltpeter.

45It was used to produce ammunition used during battle.

46And in 1816, slaves began guiding visitors on cave tours.

47At the time, the cave was still privately owned.

48One of the greatest early explorers of the cave was a slave named Stephen Bishop.

49He arrived at Mammoth Cave in 1838, when he was a teenager.

50He learned the tour paths from white guides.

51But Bishop wanted to push beyond the cave's toured areas.

52He set off to explore parts of the cave no human had ever seen.

53Bishop and a companion sought to cross an area called the Bottomless Pit.

54Its unknown darkness had stopped people from trying to go beyond it.

55But fear and darkness did not stop Bishop.

56Bishop started naming different areas of the cave that he discovered.

57Fat Man's Misery, Cleveland Avenue, and Mammoth Dome, among others.

58He was also the first to discover a river running through the cave.

59Bishop created a map of Mammoth Cave in the early 1840s.

60It included 16 kilometers of passageways.

61Most of the passages had been discovered or explored by Bishop himself.

62His map remained in use for more than 40 years.

63Bishop gained his freedom in 1856, but he died the next year at the age of 37.

64His grave lies within Mammoth Cave National Park.

65It was Bishop who described Mammoth Cave as grand, gloomy, and peculiar.

66For National Park visitors who venture into the cave today, Bishop's description remains true.

67About 500,000 people tour the cave each year.

68They are among more than 2 million visitors to the park itself.

69Mammoth Cave National Park offers campsites for those who want to sleep under the stars.

70There is also a hotel in the park.

71And there are plenty of activities outside of the cave.

72People ride horses on the more than 100 kilometers of park trails.

73They also fish and boat in the park's rivers.

74But the main draw of Mammoth Cave National Park remains the dark mystery of an underground world, with so much more to discover.

75I'm Katie Weaver.

76And I'm Ashley Thompson.

77I'm Ashley Thompson.

78I'm Ashley Thompson.

79I'm Ashley Thompson.

80I'm Ashley Thompson.

81I'm Ashley Thompson.

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84I'm Ashley Thompson.

85I'm Ashley Thompson.