Rapid Bay is a locality that includes a small seaside town and bay on the west coast of the Fleurieu Peninsula, South Australia. It lies within the District Council of Yankalilla and its township is approximately 100 km south of the state capital, Adelaide. A pair of jetties are popular attractions for recreational fishing, scuba diving and snorkelling. The bay particularly known as a site for observing leafy seadragons in the wild. Its postcode is 5204.