Is Tianci Hot Spring a natural hot spring?

Yes. According to the query Mafengwo, Jianmenguan Tianci Hot Spring is a large park with natural sulfur hot springs. It is very comfortable to soak in the hot springs in winter. Tianci Hot Spring originates from a depth of 3 kilometers in the earth's core. It was formed in the Triassic Jialingjiang Formation rock formation 230,000 years ago. It is a natural hot spring with tens of thousands of years of mineralization. The water temperature is as high as 57 degrees Celsius, and the gush height reaches 100 meters.