The Bahamian archipelago is one of the richest regions in the Caribbean province and its importance as a hot spot of biodiversity and potential centre of origination of new species in the tropical western Atlantic has been suggested. In this paper I report on the sea slugs collected during a field trip to Eleuthera Island, the Bahamas. Animals were collected from the intertidal down to five metres deep by direct sampling. Nineteen species of opisthobranchs were found including two new records to the Bahamas (Berghia stephanieae and Gastropteron vespertilium) and three putatively new species of Haminoea. Colour variation was detected on adults of the species Chelidonura hirundinina and Bulla occidentalis, the latter suggesting isolation across a reduced geographical scale. Ontogenetic variation in Philinopsis cf. pusa was found and is here documented. The uniqueness of the Bahamian biodiversity is highlighted.