The Great Boiling Pot, a spring three meters wide and 1.5 meters deep in which temperatures range from about 96 C on the surface to 102 C at the bottom. It is a must-visit in Rehai. [Photo by He Na/China Daily]

Throughout China there are more than 2,600 hot springs, and the competition to be No 1 among all these places in itself generates a huge amount of steam, but to my mind the undoubted king of them all is Rehai.

And that comes from someone who has visited many hot springs in many provinces over many years. None can compare to Rehai, in Tengchong county, Yunnan province, bordering Myanmar, which gives the visitor a totally new outlook on things thermal.

The province lies on a hotbed of geothermal activity, and Rehai, about 20 kilometers from Tengchong county, seems to be at its epicenter.

Under the earth's crust, huge pools of vapor were created by volcanic activity (Don't worry, the volcanoes are now extinct) and this spews up through cracks and has formed more than 80 hot-water springs and steam springs in Tengchong. The great majority are in Rehai, more than 10 of them as hot as 90 C.

As you approach Rehai National Natural Park, covering nine square kilometers, it becomes obvious that you are in for something special. First, there are the lush green mountains with their tropical plants that gradually seem to be enveloped in more and more steam. You could well be entering another realm. If you harbor any doubts that this is anything other than real, the pungent smell of sulfur in the air will quickly disabuse you of that notion.