斯旺西（英语：Swansea，威尔斯语：Abertawe），威尔斯语解作「Tawe河河口」，当地华人称史云斯，亦有人以其英语写法意译为天鹅海，威尔斯高尔半岛东部布里斯托尔湾畔，乃威尔斯第二大城市，也是重工业中心。斯旺西的名字来源于日耳曼语“Sweyn's Ey”，这是因为北欧海盗在历史上曾洗劫过这里。

地理上斯旺西位处威尔斯南部，十八世纪起已发展成现今规模。目前斯旺西人口逾廿二万，在威尔斯中排名第三。而人口中97%是白人。

英格兰足球超级联赛球队斯旺西城足球俱乐部就位于该市。

Swansea (/ˈswɒnzi/ SWON-zee; Welsh:Abertawe [abɛrˈtauɛ]), officially known as the City and County of Swansea (Dinas a Sir Abertawe), is a coastal city and county in Wales. It is Wales' second largest city and the twenty-fifth largest city in the UK. Swansea lies within the historic county boundaries of Glamorgan. Situated on the sandy South West Wales coast, the county area includes the Gower Peninsula and the Lliw uplands. According to its local council, the City and County of Swansea had a population of 241,300 in 2014. The last official census stated that the city, metropolitan and urban areas combined concluded to be a total of 462,000 in 2011, making it the second most populous local authority area in Wales after Cardiff. During its 19th-century industrial heyday, Swansea was a key centre of the copper industry, earning the nickname 'Copperopolis'. Since 2011, Swansea has started to expand into a larger region known as the Swansea Bay City Region. After combining with other councils, it now includes Tenby and other parts of West Wales, its population including these areas an estimated 685,051. The chairman of the new region is Sir Terry Matthews