Non-governmental organisations (NGOs) have become increasingly involved in search and rescue in the Mediterranean Sea in order to fill a gap in humanitarian protection. This article examines the legal framework of their search and rescue activities. The international law of the sea sets out an obligation to render assistance to persons in distress at sea. However, recent developments reveal that the relationship between NGO vessels rendering assistance and the affected coastal states is highly uncertain. This article addresses two particular questions: First, can NGOs navigate anywhere in order to render assistance at sea or can (coastal) states limit the rights of navigation of NGOs? Second, can coastal states give NGOs binding instructions concerning whether and how to conduct search and rescue and where to disembark the persons rescued? The article concludes that within their territorial sea, coastal states enjoy the power to determine, in a legally binding manner, how search and rescue operations are carried out, but that they may not deny NGOs access to distress scenes. Beyond their territorial sea, coastal states are neither entitled to issue binding instructions to foreign vessels nor limit their navigational freedom. In any case, all instructions have to comply with the substantive restrictions set out within the Search and Rescue regime and international human rights law.