This article focuses on the consequences of a single major international affair — the shipwreck of a French ship carrying 165 Muslim pilgrims along the southern shores of Sicily in 1716 — to address two pivotal issues in the reordering of eighteenth-­century legal and political systems: the limits of domestic sovereignty in absolutist states and the status of non-Christian polities in the theory and practice of the law of nations. Both the time and place of this episode, which had a vast resonance at the time, have broad implications for how we write about the development of modern international law. While much of the debate on the maritime dimension of the eighteenth-century law of nations focuses on the Atlantic and the Indian Oceans, we spotlight the Mediterranean, where endemic corsairing activities coexisted with age-old diplomatic and day-to-day practices of accommodation and mutual recognition between Christian and Muslim polities. Here we draw attention to shipwrecks that occurred in foreign territorial waters and their heuristic potential for better understanding controversial issues of maritime law, such as the status of shorelines, neutrality and the law of the flag. Even after the Peace of Utrecht (1713–15), which is often regarded as a watershed moment in the history of international law, these rules were far from settled and shipwrecks continued to fuel legal and philosophical battles that extended well beyond the confines of the famous controversy between supporters of mare liberum and advocates of mare clausum. The close examination of the 1716 shipwreck leads us to challenge the land/sea divide as constructed by Carl Schmitt and demonstrate that territorial waters were objects of sovereign disputes in much the same way as land territories. We also show how the emerging Eurocentric discourse about the ‘barbarity’ of non-Christian peoples and nations coexisted with intellectual, economic and diplomatic forces interested in establishing formal agreements between Western European nations, the Ottoman Empire and its North African provinces.