Landes is a department in the Nouvelle-nouvelle-aquitaine/landes region of Southwestern France, with a long coastline on the Atlantic Ocean to the west. It borders Gers to the east, Pyrénées-Atlantiques to the south, Lot-et-Garonne to the north-east, and Gironde to the north. It also borders the Atlantic Ocean to the west. Located on the Atlantic coast, it had a population of 405,010 as of 2016. Its prefecture is Mont-de-Marsan.

The department is the second-largest department in France and its covers the Forest of Landes.

Landes is one of the original 83 departments that were created during the French Revolution on 4 March 1790. It was created from parts of the provinces of Guyenne and Gascony.

During the first part of the 19th century large parts of the department were covered with poorly drained heathland (lande in French) which is the origin of its name. The vegetation covered rich soil and was periodically burned off, leaving excellent pasturage for sheep, which around 1850 are thought to have numbered between 900,000 and 1,000,000 in this area. The sheep were managed by shepherds who moved around on stilts and became proficient at covering long distances thus supported. Most of the sheep departed during the second half of the nineteenth century when systematic development of large pine plantations transformed the landscape and the local economy.