The oceanography and climate of the region is strongly influenced by conditions in the adjacent Atlantic Ocean, particularly along the continental shelf edge where where water exchange occurs between the ocean and shallow shelf seas (< 200m depth). Ocean currents support strong linkages between the Celtic Seas ecoregion and its neighbouring ecoregions. The Rockall Trough is an important pathway for the transport of warmer and more saline water from the Northeast Atlantic to more northerly ecoregions. Water transport on the shelf is primarily from south to north, and prevailing southwesterly winds from the west and south.
Four key areas constitute this ecoregion:
- The west of Scotland region consists of shallow shelf regions of the Shetland Shelf, Malin Shelf, Hebridean islands, and the coastal area between the Scottish mainland and the islands (including the Minch), and the adjacent deep‑sea region of the Faroe-Shetland Channel.
- The Celtic Sea continental shelf (< 200 m), with southern and western boundaries delimited by sharp changes in bathymetry at the shelf edge.
- The continental shelf ecoregion to the west of Ireland, which is limited westward by the Rockall Trough, with the Goban Spur and Porcupine Bank forming long extensions of the coastal continental shelf.
- The relatively shallow, semi-enclosed Irish Sea. A higher density of large cities in this region leads to a concentration of human pressures.
The Celtic Seas ecoregion is characterized by a diversity of habitats, such as an extensive slope, canyons, ridges, and seamounts that support vulnerable marine ecosystems (VMEs) concentrated within northwest Scotland, west of Ireland, and the Celtic Sea areas.
