Tourism has long been the focus of tourism marketing for countries, such as Thailand, largely because of perceived economic benefits. However, tourism is implicated to be one of the major causes of coral reef degradation. Reef tourism may impact reefs through direct activities such as diving and snorkelling, as well as indirect impacts from poorly planned coastal development and overharvesting of marine life to support tourism-associated businesses. Separating direct and indirect impacts is problematic where infrastructure exists; however, these impacts were investigated separately in the same area. In this study, we compared the prevalence of coral diseases and prevalence of signs of compromised health to distinguish direct and indirect impacts between coral reefs that have different levels of visitation and infrastructure. Surveys of reefs throughout eastern Thailand indicated poorer health of reefs near infrastructure rather than reefs at more isolated islands. Visitation intensity influenced reef health only where no infrastructure was present. We also found significant increases in nitrate, ammonium, phosphate, and total suspended sediment toward sites near infrastructure, whereas different levels of visitation made no difference to these metrics. Managers necessarily must devise a compromise between the convenience of siting tourism infrastructure close to the desired location and the ecological consequences of doing so
