Sutton-on-Sea (originally Sutton in the Marsh or Sutton le Marsh) is a small coastal village in the East Lindsey district of Lincolnshire, England. It is situated at the junction of the A52 and A1111 roads, 6 mi north-east from Alford and 2 mi south from Mablethorpe. The village is part of the civil parish of Mablethorpe and Sutton (where the population is listed).
Sutton-on-Sea is smaller than Alford.