Introduction to the Underground Forest: The forest sea at the bottom of the Changbai Valley is five kilometers east of the Changbai Mountain Ice Field and north of the Dongtian Waterfall. The valley bottom is home to towering pine trees and strewn boulders. It is known as the valley bottom family. It is the scenic spot with the lowest altitude in Changbai Mountain. It is also known as the underground forest and the crater forest. There are dense forests everywhere in the Changbai Mountain area, with towering ancient trees that block the clouds and the sun, so it is known as the "Changbai Mountain Forest Sea". According to differences in altitude, the forest sea is divided into three major forest areas: birch forest belt, coniferous birch forest belt, and coniferous and broad-leaved mixed forest belt.