Indo-Bangladesh Protocol on Inland Water Transit & Trade exists between India and Bangladesh under which inland vessels of one country can transit through the specified routes of the other country.

The existing protocol routes are:
Kolkata-Pandu-Kolkata
Kolkata-Karimganj - Kolkata
Rajshahi-Dhulian-Rajshahi
Pandu-Karimganj-Pandu
For inter-country trade, certain ports of call have been designated in each country.
These Ports of call generally act as an intermediate stops for a ship on its scheduled journey for unloading and loading of cargo or taking on supplies or fuel and maintenance and refurbishing is carried out.

These are: India

Haldia (West Bengal) ,Kolkata (West Bengal), Pandu (Assam)
Karimganj (Assam), Silghat (Assam)

Bangladesh :
Narayanganj, Khulna, Mongla, Sirajganj, Ashuganj