Karst is a type of topography. Its most notable features are sinkholes and caves. Karst topographies or landscapes have little topsoil or vegetation. They have no surface water, all water flows underground. Karst landscapes are often very scenic. They need two things to happen, water and soft rock. Karst landscapes are created when water dissolves rock. Here's how it happens: Water from rain, rivers and streams mixes with the carbon dioxide in the air and becomes slightly acidic. The somewhat acidic water corrodes soft rock, such as limestone, forming sinkholes and caves. The water that once flowed on the surface now flows underground. Roughly 8% of the Earth's land surface is karst terrain and approximately 15% has some karst features.