Reaching 132m below sea level at its deepest point, the bottom of the Karagiye Depression (also known as "Karagiye Mountain Trench") was the lowest place in all of the former Soviet Union. It occupies a large area, with a length of some 40km.
It lies in the triangle of wilderness between the roads to Zhanaozen and Kuryk (on the south coast) and the shortcut that links them. The most impressive spot in the depression is on its eastern slope, where the terrain rises abruptly to 200 metres. An observation platform halfway from Aktau to Munayshy on the southeastern road towards Zhanaozen gives a magnificent view over the area in clear weather. Take the road towards Zhanaozen from Aktau. After 30km the road descends into the depression, and passes across the undulating floor. Eventually rising up a steeper side ('attention! The dangerous section warns a sign in English) there is a good viewpoint across the depression 60km from Aktau. This gives an excellent sense of the size of the feature, whose far side is often lost in the haze.
The trench was formed as soluble limestone, dolomite and gypsum dissolved forming potholes, funnels and caves that eventually collapsed. Today the trench features many scarps and offsets and generates long rain clouds caused by the air rising above it. There is a vernal lake in the southwest of the trench and a stream rising from a drilled well that disappears back into the ground within the trench.
The trench is inhabited by Mouflon, Corsak, snakes, hares and vultures. It is the only place within the Mangyshlak plateau that mushrooms grow and these are collected by locals.
The Karagiye Depression (Black Hole) and Karakol lake (Black lake) together form the Karagiye-Karakol Nature Protection Territory . The lengthy Karakol Lake, bounded by a densebelt of reeds, and not to be confused with Koshkarkol Lake to the north of the town (which is used for water purification), is on the western edge of the Karagiye Depression, south of Aktau. It can be reached by driving 20 kilometers from Aktau along the road to Kuryk, and turning right towards the health resort (zona otdykha). The Lake is on the left of the road. The water in Karakol is extraordinarily clean and rich in fish. This attracts pelican, flamingo and other water birds, even in winter, since Karakol is a resting-place for a number of species of migrating birds on their journey from the north of Kazakhstan and Siberia.