The LGV Sud Europe Atlantique, also known as the LGV Sud-Ouest or LGV L'Océane, is a high-speed railway line between Tours and Bordeaux, in France. It is used by TGV trains operated by SNCF. It is an extension of the southern arm of the LGV Atlantique, with the western extension being LGV Bretagne-Pays de la Loire. Both extensions to the high-speed line were inaugurated on 28 February 2017, with services beginning on 2 July 2017. The line, which was at the time the biggest European railway construction project, was built by the LISEA consortium, which owns and maintains the line until 2061 and charges tolls to train companies. Trains on this line depart Paris from Gare Montparnasse.

The TGV is France's intercity high-speed rail service, operated mainly by SNCF. SNCF worked on a high-speed rail network from 1966 to 1974 and presented the project to President Georges Pompidou who approved it. Originally designed as turbotrains to be powered by gas turbines, TGV prototypes evolved into electric trains with the 1973 oil crisis. In 1976 the SNCF ordered 87 high-speed trains from Alstom. Following the inaugural service between Paris and Lyon in 1981 on the LGV Sud-Est, the network, centered on Paris, has expanded to connect major cities across France and in neighbouring countries on a combination of high-speed and conventional lines. The TGV network in France carries about 110 million passengers a year.