Unlike water, it was bone-chilling and was about minus 100 Celcius degrees. Weirdly, it was not frozen; instead, it was still flowing. Meanwhile, the water could heavily erode one's protective battle qi. Therefore, Zhang Tie had to fix his protective battle qi while swimming.
The tunnel inside the pond was as complex as a max. It was connected to many other ponds of different styles and sizes. Zhang Tie could see one pond in each a few minutes. There were odd black sands at the bottoms of those ponds which appeared to be used to plant something. Additionally, Zhang Tie saw some withered and broken roots which were thicker than 3 m in those black sands. As they had been there for so many years, they immediately turned into powders floating in the water after being lightly touched by hand.