paragraph_text: The Benedore River rises in the Benedore River Reference Area and flows generally south southeast, through the Seal Creek Reference Area, before reaching its mouth with Bass Strait within the Croajingolong National Park in the Shire of East Gippsland. The river descends over its course.

paragraph_text: Formed by the confluence of the Yeerung River West Branch and the Yeerung River East Branch, the Yeerung River rises in the Cape Conran Coastal Park, and flows generally south before reaching its mouth with Bass Strait, east of Cape Conran in the Shire of East Gippsland. The river descends over its course.

paragraph_text: Kranji Reservoir (Chinese: 克兰芝蓄水池; ) is a reservoir in the northern part of Singapore, near the Straits of Johor. It was a former freshwater river that flowed out into the sea that was dammed at its mouth to form a freshwater reservoir. It can also be classified as an estuary. The dam has a road bridging the two banks, and now prevents the sea from coming in, and is home to a marsh.

paragraph_text: Mouth Maze Cave is a large, labyrinthine river cave in Trelawny, Jamaica. It is the only exit of the Mouth River from a small valley which, during intense rainfall, becomes flooded as the flow backs up. Because of this it can only safely be visited in very dry periods.

paragraph_text: The Shire of Cohuna was a local government area on the Murray River, about north-northwest of Melbourne, the state capital of Victoria, Australia. The shire covered an area of , and existed from 1922 until 1994.

paragraph_text: The Igaraçu River, also called the Igarassu River, is a distributary of the Parnaíba River in northern Piauí state in Brazil. It flows from its origin on the Parnaiba River southwest of the city of Parnaíba to the mouth on the Atlantic Ocean near the city of Luís Correia.

paragraph_text: 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.

paragraph_text: The Coliban River, an inland perennial river of the northcentral catchment, part of the Murray-Darling basin, is located in the lower Riverina bioregion and Central Highlands region of the Australian state of Victoria. The headwaters of the Coliban River rise on the northern slopes of the Great Dividing Range and descend to flow north into the Campaspe River with the impounded Lake Eppalock.

paragraph_text: The Betka River rises south of in the Croajingolong National Park, just east of the Princes Highway, and flows generally northeast, then southeast, then east by north, before reaching its mouth with Bass Strait north of the Aerodrome in the Shire of East Gippsland. The river descends over its course.

paragraph_text: The Southern Ocean, geologically the youngest of the oceans, was formed when Antarctica and South America moved apart, opening the Drake Passage, roughly 30 million years ago. The separation of the continents allowed the formation of the Antarctic Circumpolar Current.

paragraph_text: The Syas River () is a river in Lyubytinsky District of Novgorod Oblast and Tikhvinsky and Volkhovsky Districts of Leningrad Oblast, Russia. The Syas River flows from Valdai Hills north into Lake Ladoga. A town of Syasstroy is located at its mouth. It is long, and the area of its basin . The largest tributary of the Syas is the Tikhvinka River (right).

paragraph_text: Murrumbidgee River (), a major tributary of the Murray River within the Murray–Darling basin and the second longest river in Australia. It flows through the Australian state of New South Wales and the Australian Capital Territory. It descends as it flows in a west-northwesterly direction from the foot of Peppercorn Hill in the Fiery Range of the Snowy Mountains towards its confluence with the Murray River near Boundary Bend.

paragraph_text: River Júcar flows first southward and then eastward through the towns of Cuenca, Alcalá del Júcar, Cofrentes, Alzira, Sueca and Cullera, a town located near its mouth into the Gulf of Valencia, Mediterranean Sea. It crosses the provinces of Cuenca, Albacete and Valencia

paragraph_text: The Red River is the second - largest river basin in the southern Great Plains. It rises in two branches in the Texas Panhandle and flows east, where it acts as the border between the states of Texas and Oklahoma. It forms a short border between Texas and Arkansas before entering Arkansas, turning south near Fulton, Arkansas, and flowing into Louisiana, where it flows into the Atchafalaya River. The total length of the river is 1,360 miles (2,190 km), with a mean flow of over 57,000 cubic feet per second (1,600 m / s) at the mouth.

paragraph_text: The Murray River (or River Murray) (Ngarrindjeri: Millewa, Yorta Yorta: Tongala) is Australia's longest river, at 2,508 kilometres (1,558 mi) in length. The Murray rises in the Australian Alps, draining the western side of Australia's highest mountains, and then meanders across Australia's inland plains, forming the border between the states of New South Wales and Victoria as it flows to the northwest into South Australia. It turns south at Morgan for its final 315 kilometres (196 mi), reaching the ocean at Lake Alexandrina.

paragraph_text: The river's source is Scotia Lake, a small lake east of Halfway Lake Provincial Park in Sudbury District. From there, it flows north and east, taking in two small tributaries and continuing to a point 20 kilometres southwest of the Ishpatina Ridge, where it turns south. After approximately 60 kilometres, the river flows into Lake Wanapitei in the northeastern portion of Greater Sudbury. At the south end of the lake, the river continues, flowing south until it joins the French River near the latter's mouth on Georgian Bay on Lake Huron. The river is approximately in length and is a popular wilderness canoeing route.

paragraph_text: An artificial river mouth was cut through the sand dunes adjacent to the Stirling Wetlands in 1880 to allow it to flow directly into Geographe Bay.

paragraph_text: The Saloum River rises about 105 kilometers east of Kaolack, Senegal, and flows into the Atlantic Ocean. The significant Saloum Delta is located at its mouth, which is protected as Saloum Delta National Park. The river basin lies within the Serer pre-colonial Kingdom of Saloum.

paragraph_text: Kalambo District is one of the four districts of the Rukwa Region of Tanzania, East Africa. The administrative seat is in Matai. The Kalambo River flows through the district and its mouth on Lake Tanganyika is about 15 km south of the town of Kasanga.

paragraph_text: The Shire of Kerang was a local government area located in northwestern Victoria, Australia, along the Murray River. The shire covered an area of , and existed from 1862 until 1995. From 1966 onwards, Kerang itself was managed by a separate entity; the Borough of Kerang.

Question: When did the body of water the Murray Mouth flows into come into existence?
Answer: roughly 30 million years ago