The Gulf of Maine is a roughly rectangular depression with a surface area of around , enclosed to the west and north by the North American mainland and communicating with the Atlantic Ocean to the southeast. The region's glaciation by the Laurentide Ice Sheet stripped sedimentary soil away from the coastline, leaving a shore that is predominantly rocky and scenic, lacking the sandy beaches found to the south along the Eastern Seaboard. The only significant coastal developments are located in the Boston, Portsmouth, Portland and Saint John metropolitan areas.