It was designated on 31 May 2019 by the Marine and Coastal Access Act 2009 and is a predominantly sandy area of the continental shelf, supporting molluscs and crustaceans living on and in mixed and coarse sediments.
South-West Deeps (East) covers an area of 4,676 square kilometres (1,805 sq mi) in the Western Channel and Celtic Sea, and has a maximum depth of 750 metres (2,460 ft).
A geological feature is the Celtic Sea Relict Sandbanks, which are among the largest and deepest shelf sand ridges in UK waters and is one of two MPAs to protect deep-sea bed habitats outside of Scotland.
[2] On 1 September 2022, Greenpeace UK dropped eighteen limestone boulders onto the seabed 118 miles (190 km) off the coast, to stop bottom trawling in part of the MCZ.
The move was criticised by the Marine Management Organisation (MMO) which said Greenpeace UK took part in an unlicenced activity which could put fishermen lives at risk and they were ″delivering accelerated protection measures within Marine Protection Areas.″[3]