There are 167 Sites of Special Scientific Interest (SSSIs) in Cornwall (including the Isles of Scilly). Cornwall, in the south-west of England, UK, has a population of 575,413 (2022) across an area of 3,545 km2 (875,988.6 acres), making it one of the least densely populated counties within England. The north coast of Cornwall falls on the Celtic Sea in the Atlantic Ocean, which also surrounds the Isles of Scilly, the south coast falls on the English Channel and the county is bounded by the River Tamar, forming the border with Devon, to the east. Cornish geology consists mainly of rocks from the Devonian and Carboniferous geological periods. In England the body responsible for designating SSSIs is Natural England, which chooses a site because of its fauna, flora, geological or physiographical features. Of the 167 sites designated in this Area of Search, the greatest number, 81, have been designated due to their biological interest, with 54 due to their geological interest and 32 for both. (Full list...)