Location

THE island of Ireland is situated near the edge of the European continental shelf beyond which lie the deep waters of the true North Atlantic Ocean. The seabed off Ireland's Atlantic coast forms a wide shelf that slopes down gently toward the shelf edge — arbitrarily demarcated by the 200m depth contour[1] — where the water depth increases over a relatively short distance from about 200m to between 2,500-4,000m. The slopes that plunge from the shelf edge down to the deep ocean are known as "bathyal regions". At its closest, the shelf edge is only about 30-60km from the northwest coast. The marine shelf area within the 200m depth contour to the south and west of Ireland (i.e. the Celtic Sea and Atlantic seaboard) covers approximately 200,000 square kilometres.

The broad expanse of the Malin Shelf (Malin Sea) lies to the north of Ireland, and the shallow semi-enclosed Irish Sea to the east. The western Irish Sea is marked by a deep channel (> 100m), which extends the length of the region, reaching a maximum of 315m in the northern trough known as the Beauforts Dyke. It connects to the Celtic Sea via the St George's Channel in the south and to the Malin Shelf in the north through the North Channel. West of this deep channel, fringing Ireland's east coast is a narrow, shallow (< 40m) strip.

Footnotes

1. Also taken by the OSPAR Commission to be the arbitrary "division" between Region III (Celtic Seas) and Region V (Wider Atlantic).

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