Introduction to the Underground Forest: There are seven huge craters in the park. These craters were formed by the collapse of the top after ancient volcanic eruptions. The largest crater has a diameter of 500 meters. After the ancient volcanic eruption, after thousands of years of vicissitudes of change, a large area of ​​lush virgin forest was formed at the bottom of the crater. This is the famous "underground forest". There are many such as red pine, bald pine, yellow cypress, Northeast China ash (fir) ) and other precious tree species have high scientific research, popularization value, and tourism value.