Tukastan is a central Asian country with an area of 181,154 km². The country borders Goistan Sea in the west and is situated between Darzabad, Krašnokoma and Kivkisia. The country rises slowly but steadily from the western region, which has an approx. 1,200 km long coastline along Goistan Sea, to the mountainous regions in the northeast.

The deepest point is the Ustanak Depression near Ustanak in the west of the country, a long stretched valley, the deepest point of which lies about 16 m below the mirror of Lake Goistan.

The relatively flat western parts of the country extend up to about 100 km east of Claustan and then merge into the alpine Domsa high mountains. The highest point is the Birto Peak with a height of 3.462 m. This high mountain range stretches across the eastern border to the Pamir Mountains.

The largest lake is Lake Karakul in the province of Neseba-Zobaq with an area of 284 km² and a depth of 163 m at the deepest point. The second largest lake is Lake Zorgul in the province of Stichbundi Mintaqa, about 100 km east of Istaral. The Lake Zorgul has an area of about 88 km² and a maximum depth of 137 m. The largest artificial lake is the Gregory-Kumanin-reservoir.
The Lake Karakul is crossed by the longest river of the country, the Murghab River, which originates in the Domsa mountains. The Murghab River then flows through the provinces of Stichbundi Mintaqa, Gogh and Claustan Mintaqa and flows into Goistan Sea at Slinga. The Murghab is also connected to Lake Zorgul by a tributary.
The second longest river in the country is the Amrud, which rises near Ozerogorod and is then dammed up to form the Gregory-Kumanin-reservoir. Below the dam, the Amrud flows through the provinces of Ugrigk Mintaqa and Obodan and then flows into Goistan Sea about 15 km north of Clarkav. Since the water level can be regulated via the reservoir, the river below the reservoir can be used all year round for inland navigation.