It was designated in 2016 to protect subtidal mud and sand habitats:[1] at that time the MCZ was one of three off the coast of Cumbria, the others being Allonby Bay and Cumbria Coast.
The area is 388km2, a similar size to the Isle of Wight off the south coast of England.
An unusual feature of the MCZ is that it is co-located with offshore wind turbines.
In 2019 a bye-law prohibited bottom trawling from the majority of the site.
The waters west of Walney Island have some of the largest offshore wind farms in the world.