Fundy, Bay of, large inlet of the Atlantic Ocean, c.170 mi (270 km) long and 30 to 50 mi (50–80 km) wide, between New Brunswick and SW Nova Scotia, Canada. It is famous for its tide and tidal bore; in its upper arms, Chignecto Bay and the Mínas Basin, tides reach 40 to 50 ft (12–15 m) in height and create the reversing falls of the Saint John River. At low tide, wide flats are laid bare, and the long estuaries of the rivers are drained. Many of the surrounding flats have been transformed into fertile farmland since Acadian settlers began to build dikes in the early 17th cent. Fishing and tourism are important today. St. John, N.B., is the chief port on the bay.