Tanguar Haor is one of Bangladesh's two Ramsar Wetland sites of international importance, and a real trip in its own right — about three hours west of Sylhet, then an overnight boat through the haor. In the wet season the haor is a vast lake dotted with submerged trees and fishing villages on stilts; in the dry season it shrinks to a network of beels (ponds) connected by channels.
The classic way to visit is by hired bachari — a wooden houseboat with simple accommodation and a cook on board — for two or three nights. Days are spent in dinghies birdwatching, talking with fishing communities, and exploring the channels. Trips are arranged through Sylhet-based operators; book ahead and aim for the cool months (November to February) for both birds and weather.