Joysagar tank is located at Rangpura, 5 km away from the north of
Sibsagar. One of the largest tanks in India, Joysagar tank was constructed by King Rudra Singh in 1697 in memory of his mother. It is larger than the
Sibsagar Tank, comprising an area of 318 acres of land including its four banks, out of which 155 acres, is filled with crystal clear water. An earthen water pipeline, two kilometers in length, runs from this tank to the Rangpur palace (Kareng ghar), for supplying water to the Royal Palace.
On its bank lie a fish research center, a Vishnu temple and a Shiva temple.