Introduction to the tiankeng and ground cracks: The underground river in the Grand Canyon is 50 kilometers long, the longest in the world; there are 108 shafts above the underground river, which is very spectacular.
Attraction
Introduction to the tiankeng and ground cracks: The underground river in the Grand Canyon is 50 kilometers long, the longest in the world; there are 108 shafts above the underground river, which is very spectacular.