Chapter 7 examines the history Islam on Lake Tanganyika’s shores. It explores the ways in which coastal traders adapted their religious practices to the lakeshore environment, and how new converts adapted their new religion to their pre-existing knowledge of the spiritual world. In line with recent Indian Ocean World historiography, it uses a ‘bottom-up’ approach to conversion, contesting trends in older Africanist works that focused on the conversion of elites. In this case study, this means an examination of bonds(wo)men’s importance to the spread of Islam, who, through claiming ‘freeborn’ social status, also claimed the right to convert. This allows for a greater appreciation of Islam’s influence on the lakeshore, to the extent that the lake becomes understood as an ‘Islamic Sea’ – similar in conception to the Indian Ocean over the longue durée.