The country is characterized by a very dense river network, numerous streams and canals.

An excerpt from the article 23 facts about Bangladesh
The most important rivers are the Ganges, Brahmaputra and Surma. The entire area of Bangladesh falls within the catchment area of the Indian Ocean. Where the Ganges and Brahmaputra meet and flow into the Bay of Bengal, there is a vast estuary called Ganges Delta. It is the largest river delta in the world.