How far is Liverpool from Southampton?
Southampton is spelled in Katakana in various ways: サウサンプトン; サウザンプトン; サウスハンプトン; and サザンプトン.
However, サウサンプトン is probably the most common one. For example, Keio University (one of the top-tier schools in Japan) has an international exchange program with the University of Southampton. Keio University spells the University of Southampton as サウサンプトン大学. Other major foreign study websites also use サウサンプトン.