Bridgend County Borough's mosaic of habitats includes ancient woodlands, unimproved wet grasslands, chalk grassland, river valleys and rocky gorges, coastal sand dunes and saltmarsh. These habitats support an exceptionally varied flora and fauna, including many rare and declining species. The county contains a European designated Special Area of Conservation (Kenfig SAC) and two National Nature Reserves (NNRs), Kenfig on the Glamorgan coast near Porthcawl and nearby Merthyr Mawr NNR which are part of a huge dune system, which once stretched along the coast from the River Ogmore to the Gower peninsula. Kenfig Pool, the largest freshwater lake in south Wales, lies at the heart of the reserve and is particularly valuable as a stopping off point for migrating birds.