Patos, Lagoa dos (ləgôˈə dŏs päˈtŏs) [key] [Port., = lake of the ducks], shallow tidal lagoon, c.150 mi (240 km) long and up to 30 mi (48 km) wide, Rio Grande do Sul state, SE Brazil. A wide sandbar separates it from the Atlantic Ocean. Pôrto Alegre, at the head of the lagoon, is connected with Rio Grande and the sea by a dredged shipping channel. The lagoon is an important fishing ground. Rice is grown along the western shoreline.