Colonel William Light searched for a harbour for the new colony of South Australia in 1836. He sailed a small boat along the narrow waters of the Port River and was delighted by ‘one of the finest little harbours I ever saw’.

Light’s record is one of the few that we have of the dolphins’ world before European occupation but he did not mention the dolphins. Sheltered by the Lefevre Peninsula and the mangroves the waters were safe but shallow. Some believe they were too shallow and the dolphins only came into the Port River after dredging began in the 1840s. Dolphins, however, can swim in very shallow water and because the estuary was so abundant in food it is likely that it was part of the dolphins’ home range.