The largest haor of Bangladesh is situated in Maulvi Bazar district. The size of this haor is about 20,400 hector. It contains about 47 major haors and more than 6,000 swamps or freshwater lakes, half of which are seasonal. During the dry season the swamps cover an area of approximately 4,500 ha. However, during the rainy season, the total area gets flooded, and the swamps are united as one large haor, with an area of approximately 20,400 hector. For this reason it is the largest haor in Bangladesh. Some 190,000 people live surrounding this haor area. Most of them are fisherman. They spent their lives to catch fish. Hakaluki Haor was designated an Ecologically Critical Area by the Director General of the Department of Environment, as the ecosystem is considered to have reached a critical state. In the middle time of November to February is the best time to travel this haor. In this time there come a lot of foreign birds.
Wide variety of waterfowl seen here is one of the main attractions. It also has become a significant site for bird watching. About 200 kinds of bird are seen always here. Lesser Whistling Duck, Falcated Duck, Ruddy Shell Duck, Tufted Duck, Common Shell Duck, Cotton Pygmy Goose, Greylag Geese Northern Pintail, Northern Shoveller, Graganey, Blue-winged Teal, Mallard, Gadwall, Wigeon, Common Teal, Ferruginous Pochard, Common Pochard, Indian Pond Heron, Grey Heron, Cattle Egret, Asian Open bill, Common Coot, Marsh Sandpiper, Little Ringed Plover, Golden Plover, Wood Sandpiper, Brown-Headed Gull and Black-Headed Gull are remarkable. They are looking so nice. They enrich the beauty of Hakaloki Haor. It`s natural beauty always attract the traveler.