The Bristol Channel (Welsh: Môr Hafren) is a major inlet in the island of Great Britain, separating South Wales from Devon and Somerset in South West England. It extends from the lower estuary of the River Severn (Welsh: Afon Hafren) to the North Atlantic Ocean. It takes its name from the English city of Bristol, and is over 30 miles (50 km) across at its widest point. Until Tudor times the Bristol Channel was known as the Severn Sea, and it is still known as this in both Welsh: Môr Hafren and Cornish: Mor Havren.