Odisha (formerly known as Orissa) is one of the 28 states in the Republic of India. Odisha is located in the eastern part of the Indian peninsula and the Bay of Bengal lies to its East while Chhattisgarh shares its border in the west and north-west. The state also shares geographic boundaries with West Bengal in the north-east, Jharkhand in the north and Andhra Pradesh in the south. The state is spread over an area of 1,55,707 km2 and extends for 700 km from north to south and 500 kilometres from east to west. Its coastline is 450 km long. The state is divided into 30 districts which are further subdivided into 314 blocks called tahasil.
Physiographically, Odisha consists of coastal plains, central plateaus, central hilly regions, flood plains, and uplands. About a third of the state has a green cover.
Mahanadi is the largest river of the state and its catchment area covers 42% of the state. There are several other significant rivers that flow through the state such as the Subarnarekha, the Brahmani, the Baitarani, and the Vansadhara.
Chilika Lake, located on the east coast of the state is one of the world's largest brackish water lagoons. Besides that there are several other lakes in the state such as Anshupa, Tampara, and Kanjia.
Geologically the state is home to some of the oldest rocks of the world. Odisha also consists of two cratons (e.g. North Odisha Craton and Western Odisha Craton), which are sedimentary formations from the Cretaceous period. They are found in many places and are home to coal deposits. The coasts are made up predominantly of deltaic sediments of Mahanadi, Brahmani, Baitarani, Subarnarekha rivers of Quaternary age.