Karst areas in the territory of Kohila municipality are quite widespread, and not only in swamp areas. The landscape included many attractive forms of karst. Here we can find alvar karst areas, karst fields, sinkholes, karst springs, karst caves, etc.
Four karst areas are taken under protection.

Aandu karst region

with the surface area of 15.9 ha

located in Aandu village. The karst region has a karst valley with northern-southern direction, 800 m long (also estimated to be 1.5 km long) and 2 m deep. Water of Teemanti stream is absorbed by three sinkholes, the biggest of which is 2 m deep and 17 m wide. During periods of high water, through the karst valley the water reaches Urge cavity which is 20 m wide and 2 m deep with the absorption capacity of 14 l/s.

Hageri karst region

with the surface area of 2.1 ha

is located in Hageri hamlet and is highly visible. Hageri karst cavity is the largest karst form in Raplamaa. Its depth is 2.5 m. The even surface of the karst cavity has numerous holes. The biggest sinkhole is over 30 m wide, with absorbing capacity of over 60 l/s, and the entire karst area is 200 l/s. The karst region is fed with water coming through the main ditch starting in Rabivere marsh, and during high water periods it forms a karst lake the water surface area of which may exceed 2 ha, while in summer it is dry. The underground river that starts in the cavity and flows approximately in northern direction is 1.5 km long, opening up as springs. During periods of high water in the place of the underground riverbed the water flows along a narrow depression, that starts with the 0.5 km long chain of sinkholes on its bottom.

Nõmme gorge

(Nõmme sinkhole)

is located in Mälivere village 1300 m southwest from Lohu train station. Absorption capacity of the gorge is humble, around 20 l/s according to estimations of geologists. During high water periods a small temporary body of water may be formed here. Absorbed water moves along layers of flagstone in the eastern direction and surfaces as a spring on the bottom of the Keila River in Mälivere village.

Urge gorge

with the surface area of 1.8 ha

is located in Kadaka village. It absorbs the stream that starts from Lake Kõnnu and flows in northern direction, but after Teeriku farm turns to the east. The barranca partly overtaken by wild plants absorbs water in the area exceeding 100 metres, finishing with two partially conjoined funnels with diameter of  15-25 m and depth over 2 m. Total water absorption capacity of the karst valley is assessed as a large one, over 200 l/s. High water periods result in floods.