C1800 Beneath freshwater lake

In the calm water, with a depth of 500 m, Xia Lei stopped diving.

Not far below him was the bottom of the lake. At the center of the lake, there was a cave. It wasn't very big. It was tens of meters in diameter and was shaped like an oval.

There was a cave under the water, which was normal.

However, this cave was definitely abnormal, because its lake water was dark green