Karst is an area of land made up of limestone. Limestone, also known as chalk or calcium carbonate, is a soft rock that dissolves in water. As rainwater seeps into the rock, it slowly erodes. Karst landscapes can be worn away from the top or dissolved from a weak point inside the rock.

Karst landscapes feature caves, underground streams and sinkholes on the surface. Where erosion has worn away the land above ground, steep rocky cliffs are visible.

Shilin is a karst formation in southern China. In Chinese, shilin means stone forest. Shilin got its name because the tall rocks that formed due to erosion look like stone trees. Shilin is part of a larger karst landscape called the South China Karst, which spreads across the Chinese provinces of Guangxi, Guizhou, and Yunnan.

In Mexico's Yucatan Peninsula, you can find cenotes, which are karst sinkholes that have filled with water. Sometimes, cenotes connect to waterways underground. Mexicans and tourists use the cenotes as cool, pristine swimming pools.