Yankalilla Bay is a long, wide bay in south-eastern South Australia, on the Fleurieu Peninsula. It is on the south-eastern coast of the Gulf St Vincent, as it opens into the Southern Ocean. Three rivers discharge into the bay: the Bungala River, (whose mouth is at Lady Bay) and Carrickalinga Creek. The rivers can adversely affect the ecology of the sea, in particular the health of the reef and seagrass. Normanville Beach and Carrickalinga Reef.