The most widespread use of satellite imagery has been the mapping and inventory of coastal resources (e.g. Ku- chler et al. 1986; Bastin 1988; Luczkovich et al. 1993). Maps of reef habitat are a useful planning tool which, among other uses, allows management boundaries to be located (Kenchington and Claasen 1988) and the identification of representative reef systems (McNeill 1994). This paper is specifically concerned with the use of remote sensing for mapping coral-reef systems.