From the Wikipedia page 
Pyrénées-Atlantiques (French pronunciation: [piʁene atlɑ̃tik]; Gascon: Pirenèus-Atlantics; Basque: Pirinio Atlantiarrak or Pirinio Atlantikoak) is a department in the region of Nouvelle-Aquitaine, in southwestern France. It takes its name from the Pyrenees mountains and the Atlantic Ocean. It covers the French Basque Country and the Béarn.
Basses-Pyrénées is one of the original 83 departments of France created during the French Revolution, on 4 March 1790. It was created out of parts belonging to the former greater province of Guyenne and Gascony, as well as the Béarn-Navarre (still, at least nominally, Kingdom of Navarre), i.e. the Basques provinces of Basse-Navarre, Labourd, Bayonne (detached a few years before from Labourd), and Soule, and Béarn.
Pyrénées-Atlantiques is part of the Nouvelle-Aquitaine region of Southwest France. It is bordered by the Landes, Hautes-Pyrénées, Gers departments and the Bay of Biscay. Principal settlements include Pau, Oloron-Sainte-Marie, Orthez, Biarritz, Bayonne, Anglet, Urrugne, Saint-Jean-de-Luz and Hendaye. Lac Gentau is located here, as are the Lacs de Carnau.