La Certosa (Italian: Isola della Certosa) is an island in the Venetian Lagoon, northern Italy. It is located north-west of Venice, less than 250 meters from San Pietro di Castello and little more than 500 meters from the Venice; a ca. 20 m-wide channel separates it from the Vignole island. La Certosa has a surface of some 22 ha.
The island housed a community of Augustinian friars starting from 1199. After two centuries, the abandoned island was ceded to the Carthusians, the previous religious edifice being restored from 1490 to 1505. After the Napoleonic conquest of Venice, it became a military installation.
The 17th century Castello delle Polveri ("Powder Castle"), the only historical edifice remained today, has been restored from the late 1990s.