In Wales, national nature reserves (NNRs) are selected and designated by Natural Resources Wales (NRW; formerly the Countryside Council for Wales). There are 76 reserves, all of which are also SSSIs. They cover , or less than 1.5% of the land area of Wales. They range in size from Dan yr Ogof at to Berwyn which covers . A national nature reserve is designated because of its special biological, geological, habitat or landscape value and most in Wales are open to the public. They include upland and lowland areas, several offshore islands and in some cases estuarine and intertidal zones.
Although the majority of sites are managed by NRW, a number are managed by other bodies, mainly in the public and wildlife charity sectors, including: