Nalban is a lake-and-creek area on the edge of the East Kolkata Wetlands, with groves, picnic space, and a calm stretch of water used for boating. Paddleboats, rowboats, and shikaras make it a simple family outing away from the denser parts of the city.
It is best treated as a relaxed break rather than a major sight. Go for open water, greenery, and a slower few hours near the wetlands.