St. Malo, Gulf of

a gulf of the English Channel, off the northwestern coast of France. It is 110 km long and approximately 125 km wide at its entrance; the maximum depth is 51 m. The gulf is known for its high tides, which sometimes reach 15 m. In 1967 an experimental tidal electric power plant with a capacity of 240 MW was constructed at the mouth of the Rance River, which empties into the gulf.