Ratargul lies on the Gowain river in Gowainghat, about 26 km from Sylhet city, and is often called the Sundarbans of Sylhet. The forest, mostly koroch trees, stands in water all year round: 20 to 30 feet deep in the monsoon and around 10 feet the rest of the time. About 504 acres of it were declared a wildlife sanctuary in 2015.
The only way through is by small boat, gliding between the trunks under the canopy. A watch tower gives a view over the whole forest. Look for kingfishers, herons and egrets, monkeys and water monitors; migratory birds arrive in winter.
Most people come in the monsoon, from May to early October, when the forest floods. Visitors need the forest office's permission, which is arranged on arrival.