Brazilian submarine Rio Grande do Sul (S11)

Rio Grande do Sul (S11) may refer to one of the following submarines of the Brazilian Navy:


 * Brazilian submarine Rio Grande do Sul (S11) (Balao class), the former American Balao-class submarine USS Sand Lance (SS-381); in Brazilian Navy service, 1963–1972; cannibalized for spare parts and scrapped by 1975
 * Brazilian submarine Rio Grande do Sul (S11) (Tench class), the former American Tench-class submarine USS Sea Leopard (SS-483); in Brazilian Navy service, 1973–1993