borough (district), administrative and historic county of Cornwall, extreme southwestern England, in the central part of the county. Restormel borough spans the peninsular county and is thus bordered by the Atlantic Ocean to the northwest and St. Austell Bay and the English Channel to the south.

Gently rolling and elevated, the interior of Restormel is composed of hard sandstone soils. Inland from the south and dominating the landscape, however, is a granite intrusive called the Hensbarrow Downs, 600 to 1,000 feet (180 to 300 metres) high. These bleak downs usually support only a grass cover. Even the lower-lying sandstone areas grazed by dairy and beef cattle are largely barren of trees because of the windswept environment.

The small ports of Fowey and Mevagissey on the south coast are adjacent to limited low-lying areas that support some fruits and market garden produce. Sand dunes and ocean breakers below the cliffs at Newquay on the northern coast are popular with vacationers and surfers. Fowey was the principal port of Cornwall during the Middle Ages, and later (like Mevagissey) it was a centre for smuggling. Contemporary Fowey exports England's principal kaolin (china clay) deposits, quarried in the nearby Hensbarrow Downs. Mevagissey is a fishing port (primarily mackerel and pilchard). St. Austell, the processing center for the kaolin deposits, is the administrative centre. Area 175 square miles (452 square km). Pop. (2001) 95,547.