Celtic Sea - Limits

Limits

There are no land features to divide the Celtic Sea from the open Atlantic Ocean to the south and west. For these limits, Holt suggested the 200 fathom (366 m) marine contour and the island of Ushant off the tip of Brittany.

The definition approved by 1974 by the Hydrographer of the Royal Navy for use in Admiralty Charts was "bounded roughly by lines joining Ushant, Land's End, Hartland Point, Lundy Island, St. Govan's Head and Rosslare, thence following the Irish coast south to Mizen Head and then along the 200-metre isobath to approximately the latitude of Ushant."

The International Hydrographic Organization defines the limits of the Celtic Sea as follows:

On the North. The Southern limit of the Irish Sea, the South coast of Ireland, thence from Mizen Head a line drawn to a position 51°0′N 11°30′W / 51°N 11.5°W / 51; -11.5.

On the West and South. A line from the position 51°0′N 11°30′W / 51°N 11.5°W / 51; -11.5 South to 49°N, thence to latitude 46°30'N on the Western limit of the Bay of Biscay, thence along that line to Penmarch Point.

On the East. The Western limit of the English Channel and the Western limit of the Bristol Channel .