Swansea is a coastal city and the second-largest city of Wales. It forms a principal area, officially known as the City and County of Swansea. The city is the twenty-fifth largest in the United Kingdom. Located along Swansea Bay in southwest Wales, with the principal area covering the Gower Peninsula, it is part of the Swansea Bay region and part of the historic county of Glamorgan and the ancient Welsh commote of Gŵyr.