Plymouth Sound and Estuaries SAC

Status: Designated


Site overview

Plymouth Sound and Estuaries, on the south-west coast of England, is protected because of the sandbanks found here. Eelgrass meadows grow on top of these sandy patches and their long roots help stabilise the seabed. The estuaries here are ria estuaries, which are drowned river valleys. As a result salty water mixes with fresh water creating a unique environment. Rocky reefs in diluted salt water are rare, but they are found here. The extensive mudflats here are also highly productive and provide important feeding grounds for internationally significant numbers of wildfowl. Nationally scarce fan mussels are also found here, just beside the lidoat the hoe! 

MPA Type

Special Area of Conservation

Special Areas of Conservation (SACs) are strictly protected sites designated under European legislation. They contribute both to the UK MPA network and set up to protect habitat types and species considered to be most in need of conservation at a European level (excluding birds).

Designation date

1 October 1996

Surface Area

63.88 km2 (24.66 mi.2)


279.26 km (173.52 mi.)

  • Allis shad (Alosa alosa)

    A rare and declining fish species which is part of the herring family. It grows in coastal waters and estuaries but migrates into rivers to breed. Almost all adults die after laying and fertilising the eggs.

  • Atlantic salt meadows (Glauco-Puccinellietalia maritimae)

    Areas with specially adapted plants found in the upper reaches of saltmarshes that are not always reached by the tide. The habitat is used for grazing, but is also very important for birds.

  • Estuaries

    The downstream part of a river, where it nears the sea, which is influenced by the tide These complex habitats can include areas always submerged by the tide as well as those exposed at low tide. They can be exceptionally important feeding and breeding ar

  • Intertidal mudflats and sandflats (Mudflats and sandflats not covered by seawater at low tide)
  • Subtidal sandbanks

    Sandbanks which are slightly covered by sea water all the time

  • Shallow inlets and bays (Shallow inlets and bays)
  • Reefs

    Areas where the bedrock, stable boulders and cobbles or structures created by animals arise from the surrounding seabed. They attract and provide a home to a huge variety of plant and animal life.

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The Marine Conservation Society has been heavily active in Seasearch diving the site, particularly since 2012.

Learn more about Seasearch

Did you know?…

Over half a million people have voiced their support for ‘marine protected area’ designation in the UK through our campaigns

Over 500,000 records of undersea species and habitats have been collected by volunteer Seasearch divers

To the shelf limits, Scotland has 61% of UK waters, of which 23% are now in existing or new ‘marine protected areas’