Pasur River  a big river in the sundarbans area as an extension of the Rupsa river. South of khulna, the bhairab or the Rupsa flows further south and is renamed as Pasur near Chalna and falls into the bay of bengal flowing to the right of Trikona and Dubla islands. South of mongla upazila the river flows into the Sundarbans. The maximum flow of the gorai-madhumati passes into this river through the nabaganga. The Pasur is placed after the meghna in size in the deltaic region. The river is joined by Mongla canal at about 32 km south from Chalna. Flowing further south the river meets the shibsa at about 32 km north from its mouth and debouches into the sea keeping its original name Pasur.

The river is very deep and navigable throughout the year and large marine ships can easily enter Mongla Sea Port through it. The Pasur is an important river route through which Khulna-Barisal steamboats and other vessels ply. The river is about 460m wide at Rupsa, about 790m at Bajuyan and about 2.44 km at the confluence of the Pasur-Shibsa. The total length of the river is about 142 km. The Pasur and all its distributaries are tidal channels. [Masud Hasan Chowdhury]

See map in ganges-padma river system.