How long is the longest karst cave group in the world?

The longest karst cave group in the world is mammoth cave in Kentucky Cave National Park. Mammoth cave consists of 255 caves, divided into five layers, which can be connected up and down, left and right. The total length of the cave is 252 kilometers, which is a tortuous and deep underground maze. There are 77 underground halls in the cave, the most famous of which are Central Hall, Chief Hall, Big Bat Hall, Star Hall and Wedding Hall. The central hall is located in the middle of the cave group, which has all kinds of well-equipped tourist service facilities. The Chief Hall is the tallest hall among them, with a length of 163m, a width of 87m and a height of 38m, which can accommodate thousands of people.

In the mammoth cave, a dry limestone body poured down from the top of the cave. It looks like a hanging waterfall, and people call it "frozen Niagara Falls". In addition, there are seven real waterfalls in the cave, which are distributed in three underground rivers and an underground lake. Some water rumbles and water drops splash; Some are deep and quiet, such as mirrors. The most famous are the Dead Sea, Echo River and Forgotten Lake. During May ~ 10 every year, the water level rises, and people find it interesting to go boating on the lake and swim in the underground river.

The largest underground cave in the world is the big house cave in Carlsbad Cave, Mexico, USA. Carlsbad Cave is a strange underground world: the towering cave can accommodate a skyscraper; The winding tunnel is like an underground maze; Colorful stalagmites and stalactites are strange, just like the wonders of the world.