The Pembrokeshire Marine SAC is the third largest marine SAC in the UK, covering an area of 138,069 ha. The site extends from near Abereiddy in north Pembrokeshire all the way round to Manorbier in South Pembrokeshire and includes the coast of the islands of Ramsey, Skomer, Grassholm, Skokholm, the Bishops and Clerks, and The Smalls (21 miles offshore). It also encompasses almost the entire Milford Haven Waterway. The landward boundary of the SAC mostly follows the extreme high water mark.

To see a map of the other marine SACs in Wales, click here. For more detail go to the Countryside Council for Wales to view their maps of protected sites.

The Pembrokeshire Marine SAC overlaps with other important European sites. These are called Special Protection Areas (SPA's) that are specifically designated for the protection of birds (under the 1979 EC Bird's Directive). SPA's that occur within the SAC and contain an intertidal element include Skokholm and Skomer, Grassholm, the St David's Peninsula Coast and Ramsey. SAC's and SPA's are both also known as European Marine Sites.

The Skomer Marine Nature Reserve (a UK conservation designation) also occurs within the site. Under the Marine & Coastal Access Act 2009 this designation will be changed to become the first Marine Conservation Zone in Wales. This marine protected area is currently managed by the Countryside Council for Wales; the underwater studies set up here are pioneering marine ecology research.