East Cote Blanche Bay (kot BLAHNSH), arm of the Gulf of Mexico, in St. Mary parish, S La., c.30 mi/48 km SSE of New Iberia; 12 mi/19 km wide at entrance; 29°33'N 91°38'W. Passage connects it with W. Cote Blanche Bay to NW. Marsh Isl. is to W, mainland to N and E, gulf to S, Atchafalaya Delta to E. Oil and gas field nearby.