Rapid Bay (postcode 5204) is a small seaside town in the southwest of the Fleurieu Peninsula, South Australia. It is approximately 100 km south of the state capital Adelaide. Rapid Bay lies within the District Council of Yankalilla.
Colonel William Light made his first landfall on mainland South Australia at Rapid Bay on 8 September 1836. The site was named after his ship, the brig Rapid (162 tons). To mark this historic landfall the captain’s initials, W.L., were carved into large boulder – a replica is visible in the township, while the original is stored in the South Australian Museum, in Adelaide. The first European child born on mainland South Australia was delivered at Rapid Bay on November 7, 1836. His name was John Rapid Hoare.
For a short time Rapid Bay was considered a potential site for the new state capital, but with the discovery of the Adelaide Plains it faded into quiet obscurity. BHP established a limestone mine here in the early 1940s, establishing the town in its current layout.
Rapid Bay is known for its imposing cliffs, caves and beaches and for the long jetty with a local leafy seadragon population. Rapid Bay features in Kaurna Aboriginal creation story, most notably in relation to Tjilbruke (also Tjirbruki). The former HMAS Hobart, a guided missile destroyer, was sunk in 30 metres of water 3 km from shore, and is a popular scuba diving site.