An everglade might be deﬁned most easily as a swampy tract covered with tall grass and dotted with occasional trees. In practice, however, the word almost always refers to the grand marsh of southern Florida, which is so ﬂat that a broad sheet of water ﬂows slowly across it on the way to the sea—a river with a valley so shallow it is measured in inches. The system is so ﬁnely balanced that minute variations in elevation can lead to dramatic changes in ﬂora and fauna. The etymology of everglade is obscure, but “ever” may have been used to mean “interminable.” If so, it was a misnomer, for changes in land use and irrigation north of the Everglades have altered the ﬂow of water and driven the area’s unique plants, animals, and processes to the point of extinction. As the twenty-ﬁrst century begins, it is the site of the largest attempt at ecosystem restoration any place on the face of the globe, an expensive and desperate attempt to keep the concept of everglade alive.