The Qiqihar natural well was caused by geological subsidence on the Yucatan Peninsula, which exposed her clear groundwater. It is also the third longest underground hole in the world, and there are various cold water fishes in the water, because most of the water holes are very dark, and some fish have degraded without vision, which is very incredible. In addition, the remains of water-deep flora and fauna of ancient times can be seen, including human skulls, and the Mayans believe that the crater is the entrance to the underground world, often sacrificed here, so it is also quite mysterious.