Allonby Bay is a crescent-shaped bay of the Solway Firth on the north-western shore of Cumbria, England.[1][2] The bay is 5.5 miles (8.9 km) across. Its northern point is at Dubmill, between the village of Mawbray and the hamlet of Salta, and its southern end is just to the north of Maryport, near the village of Crosscanonby. The B5300 coast road follows the shoreline of Allonby Bay, running between Silloth in the north and Maryport in the south.
As an inlet of the Solway Firth, Allonby Bay is also part of the Irish Sea. The bay is named after the village of Allonby, which sits roughly in the centre of the shoreline.