Chinampa (Nahuatl languages: chināmitl [tʃiˈnaːmitɬ]) is a technique used in Mesoamerican agriculture which relies on small, rectangular areas of fertile arable land to grow crops on the shallow lake beds in the Valley of Mexico. The word chinampa has Nahuatl origins, chinampa meaning “in the fence of reeds”. They are built up on wetlands of a lake or freshwater swamp for agricultural purposes, and their proportions ensure optimal moisture retention. This method was also used and occupied most of Lake Xochimilco. The United Nations designated it a Globally Important Agricultural Heritage System in 2018.
Although different technologies existed during the Post-classic and Colonial periods in the basin, chinampas have raised many questions about agricultural production and political development. After the Aztec Triple Alliance formed, the conquest of southern basin city-states, such as Xochimilco, was one of the first strategies of imperial expansion. Before this time, farmers maintained small-scale chinampas adjacent to their households and communities in the freshwater lakes of Xochimilco and Chalco. The Aztecs did not invent the chinampa technology but rather were the first to develop it to a large scale cultivation. Sometimes referred to as "floating gardens," chinampas are artificial islands that were created by interweaving reeds with stakes beneath the lake's surface, creating underwater fences. A buildup of soil and aquatic vegetation would be piled into these "fences" until the top layer of soil was visible on the water's surface.