Query: What ocean is Saint Helena located in?
Context: Saint Helena (/ˌseɪnt həˈliːnə/ SAYNT-hə-LEE-nə) is a volcanic tropical island in the South Atlantic Ocean, 4,000 kilometres (2,500 mi) east of Rio de Janeiro and 1,950 kilometres (1,210 mi) west of the Cunene River, which marks the border between Namibia and Angola in southwestern Africa. It is part of the British Overseas Territory of Saint Helena, Ascension and Tristan da Cunha.