Penguins have been exhibited at Edinburgh Zoo since 1914 and the Zoo is well-known for its expertise in keeping and breeding these birds, in particular the King penguin Aptenodvtes patagonica and Gentoo penguin Pygoscelis papua. Remodelling and extension of the existing penguin enclosure was completed in 1992 and a young group of Macaroni penguins Eudyptes chrysolophus has been added to the exhibit. The new enclosure is believed to be the largest penguin enclosure in existence and the larger and deeper pool has allowed the birds greater opportunity for swimming. The condition of King and Gentoo penguins has visibly improved and both species have produced young in the two breeding seasons since the reopening. In this paper the planning and design of the enclosure and water filtration is described, together with brief notes on the management of the birds.