The Celtic Sea is part of the North Atlantic Ocean and lies south of Ireland. It borders St. George’s Channel, the Bristol Channel, the English Channel and the Bay of Biscay. It has a surface area of around 300,000 km2. The sea was named after the Celts, a group of people that inhabited Ireland ages ago, by E. W. L. Holt in 1921. The name was first adopted in French speaking countries, before becoming common in English speaking countries. The Sea has oil and gas reserves, as well as a rich fishery. Whales and dolphins are also frequently spotted in the area.