Murray Mouth is the point at which the River Murray meets the Southern Ocean. The Murray Mouth's location is changeable. Historical records show that the channel out to sea moves along the sand dunes over time. At times of greater river flow and rough seas, the two bodies of water would erode the sand dunes to create a new channel leaving the old one to silt and disappear. Description The mouth of the Murray River is about south east of Goolwa and about south-south-east of the Adelaide city centre in the gazetted localities of Coorong and Goolwa South. The mouth is an opening in the coastal dune system which separates the river system from the ocean and which extends from near Goolwa in a south-easterly direction along the continental coastline for about . The mouth divides the dune system into two peninsulas. The peninsula on the west side is Sir Richard Peninsula which terminates at the mouth with a point named Pullen Spit. The peninsula on the east side is Younghusband Peninsula which terminates at the mouth with a point known in some sources as Sleepy Hollow. Water flows throughout the mouth from two directions. Firstly, the flow from the west passes along a passage known as the Goolwa Channel which is bounded by Hindmarsh Island to its north side. Secondly, the flow from the east passes along a passage known as the Coorong Channel. The Coorong Channel itself is fed by the Mundoo Channel which passes between Hindmarsh Island and Mundoo Island to the north, and by the Tauwitchere Channel to the east. Natural history From the Pleistocene about 2.5 million years ago, the Murray River terminated in a freshwater lake called Lake Bungunnia which included the area now occupied by the South Australia/New South Wales border. The lake drained less than a million years ago, creating the current course. It was suggested that the Murray may have taken a different course to the ocean, via Burra, South Australia and emptied into the Spencer Gulf, before being 'defeated' by the rise of the Mt Lofty Ranges. This has been studied by analysing the uplift date of the Mt Lofty Ranges and other geological data and found that this was not likely to be the case. History European discovery and use During expeditions in 1829–30, Charles Sturt explored the Murray and its westward-flowing tributaries, finding that the mouth of the