The longest river in India is the Ganga River (also known as the Ganges). It flows for about 2,525 kilometers (1,569 miles) within India, originating from the Gangotri Glacier in the state of Uttarakhand and flowing through the northern plains before emptying into the Bay of Bengal.
If we consider only rivers flowing entirely within India, the Ganga holds the title. However, in terms of total length (including portions outside India), the Indus River is technically longer, at approximately 3,180 kilometers (1,976 miles), but it flows mainly through Pakistan.
Thus:
- Longest river within India: Ganga – 2,525 km
- Longest river originating in India but extending outside: Indus – 3,180 km