The longest cave is Mammoth Cave in Kentucky with 349 miles (563 km) of passageways.

The deepest cave is Krubera (Voronja) Cave in the Republic of Abkhasia at over 5,600 feet (1,710 m) deep, recently explored to this depth in 2001 (Gee 1994).

The largest cave chamber is in Sarawak Cavern in Sarawak, Malaysia. This room is approximately 2,300 feet (700 m) long, 1,300 feet (396 m) wide, and at least 230 feet (70 m) high.

The vast majority of caves form in soluble rocks such as limestone, dolomite, gypsum, and marble, but caves also form in other types of rock.