From: Gosselink, 1979; LDWF
Vermilion Bay is located on the eastern boundary of the Chenier Coastal Plain along the central Louisiana coast, and the Atchafalaya Basin is located in the central part of the coastal zone, west of the Terrebonne Basin. Vermilion Bay proper is separated from the Gulf of Mexico by Marsh Island and water exchange takes place via southwest pass. Extending to the east, Vermilion Bay branches into West and East Cote Blanche Bays before connecting with Atchafalaya Bay and opening to the Gulf of Mexico. Freshwater inflow to Vermilion Bay comes from the Vermilion River, while Atchafalaya Bay receives freshwater input from the Atchafalaya River. These freshwater inflows combined with the 'reefs' of the Atchafalaya River Delta, act to maintain a relatively freshwater character to the Vermilion-Atchafalaya Bay complex.
The southwestern shore of Vermilion Bay is a State Wildlife Refuge owned and maintained by the state of Louisiana. The area is home to a variety of marsh wildlife. Alligators, shorebirds, wading birds, and marine life such as shrimp and other mammals are common.