[2] E. W. L. Holt proposed the name at a 1921 meeting of fisheries experts from Great Britain, France, and Ireland in Dublin.

In the opposite direction, sand ridges pointing southwest have a similar height, separated by troughs approximately 50 m (160 ft) deeper.

The area has potential for 50 GW of floating wind farms, and TotalEnergies plans a project with almost 100 MW.

[11][12] 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 (370 m; 1,200 ft) marine contour and the island of Ushant off the tip of Brittany.

The definition approved in 1974 by the UK Hydrographer of the 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.