Behavioural changes are often regarded as a key indicator of the effect of human disturbances on animals, and responses are commonly used as indices of disturbances. Tourism is an increasingly common source of disturbance to wild animals, including marine mammals. Swim-with-seals (SWS) tourism is an emerging industry that has grown in countries such as New Zealand, Australia and South Africa. We studied behavioural impacts of SWS in the Robberg Marine Protected Area (Western Cape, South Africa) on the adjacent Cape fur seal Arctocephalus pusillus pusillus colony through a modified Before-After-Control- Impact (BACI) behavioural study designed for simultaneous observations of impact and control sites (site factor) and before, during and after SWS activities (phase factor). Elevated observations were carried out at distances from the sites using sequential photography of the colony to enumerate seals in different behavioural categories, allowing comparisons between sites and between...