The Surma-Meghna River System is a river complex in South Asia, one of the three that form the Ganges Delta, the largest on earth.^{[citation needed]} It rises in the Manipur Hills of northeast India as the Barak River and flows west becoming the Surma River and then flows south as the Meghna River, a total of 946 km (669 km within Bangladesh) to the Bay of Bengal.

From its source in the Manipur Hills of India, near Mao Songsang, the river is known as the Barak River. Near its source, the river receives a lot of little hill streams, including the Gumti, Howrah, Kagni, Senai Buri, Hari Mangal, Kakrai, Kurulia, Balujhuri, Shonaichhari and Durduria. It flows west through Manipur State, then southwest leaving Manipur and entering Mizoram State.

In Mizoram State the Barak flows southwest then veers abruptly north when joined by a north flowing stream and flows into Assam State where it turns westward again near Lakhipur as it enters the plains. It then flows west past the town of Silchar where it is joined by the Madhura River. After Silchar, it flows for about 30-odd kilometres & near Badarpur, it divides itself into the Surma River and the Kushiyara River and enters Bangladesh. The principal tributaries of the Barak in India are the Jiri, the Dhaleshwari (Tlawng), the Singla, the Longai, the Madhura, the Sonai (Tuirial), the Rukni and the Katakhal.

The Meghna River (Bengali: মেঘনা নদী) is an important river in Bangladesh, one of the three that forms the Ganges Delta, the largest on earth fanning out to the Bay of Bengal. Being a part of the Surma-Meghna River System, Meghna is formed inside Bangladesh by the joining of different rivers originating from the hilly regions of eastern India. The river meets Padma River in Chandpur District. The river ultimately flows into the Bay of Bengal in Bhola District.

Major tributaries of the Meghna include the Dhaleshwari River, Gumti River, and Feni River. The Meghna empties into the Bay of Bengal via four principal mouths, named Tetulia, Shahbazpur, Hatia, and Bamni.

The Meghna is the widest river among those that flow completely inside the boundaries of Bangladesh. At one point near Bhola, Meghna is 12 km wide. In its lower reaches this river follows almost a straight line in its path. Despite its very calm and quiet look, this river is the cause of many deaths every year. Several ferry sinkings in the past have killed hundreds, like the MV Salahuddin-2 and the MV Nasrin-1. Near Chandpur it is very dangerous.