For many years, the scientific community has focused on the negative impacts of humans on the oceans. Recently, with major weather events such as the 2005 hurricane season, as well as the other issues described below, it has become clear that human health is inextricably linked to ocean health, and vice versa. Because of the oceans’ vastness and the dependence of an increasing number of humans on the oceans, this inter-relationship between human health and ocean health is shared by all humans and other creatures on Earth (Epstein et al., 1994; Epstein, 1995; Kovats et al., 1998; National Research Council [NRC], 1999; Anonymous, 2001; Knap et al., 2002; Stegeman et al., 2002; Tibbets, 2002; Dewailly, 2002; Pew Oceans Commission, 2003; Tyson et al., 2004; U.S. Commission on Ocean Policy, 2004; Sandifer et al., 2004; Tibbets, 2005; Bowen et al., in press; Fleming et al., in press). To address the complex relationship between the oceans and human health, a new type of interdisciplinary science is needed, one that brings together oceanographic and biomedical scientists, as well as other disciplines. This special issue of Oceanography contains a series of articles and illustrative case studies by an interdisciplinary group of scientists on key issues of oceans and human health.