The region's boundaries mostly follow those set out in international law. In the eastern part of the region, the project's seaward boundary is the median line between France, Ireland and Wales. In the western part of the region, the boundary is the limit of the UK's Exclusive Economic Zone. At the south eastern edge we have drawn a line due south from the Dorset/Hampshire County boundary to the median line between the UK and France. At the north eastern edge we have drawn a line due north from the North Somerset and Bristol boundary to the median line between England and Wales.

This is a vast area of sea, but the size gives us several advantages. It gives us a degree of flexibility to locate Marine Conservation Zones so as to minimise impact to stakeholders and it is more cost-effective than a smaller project.