This book provides an accessible and detailed examination of the intricate legal frameworks governing maritime security and jurisdiction at sea, systematically exploring the impact of key international law concepts on maritime security. As maritime security threats increasingly intersect with broader global challenges, including illegal fishing, climate migration and forced labour, this book fills critical gaps in legal understanding. Through clear explanations and real-world examples, it navigates the fragmented landscape of maritime law and enforcement. Divided into three parts, the first section guides readers through maritime zones, from internal waters to the high seas, clarifying the legal rights and responsibilities of coastal and flag states as established in combating maritime crimes. The second part addresses contemporary maritime crimes, such as piracy, drug and human trafficking, migrant smuggling, terrorism and environmental offences, providing practical insights into international legal regulations and enforcement mechanisms. Finally, the third part explores the lawful use of force at sea and examines the increasing overlap between maritime law enforcement and human rights obligations. This book bridges the gap between theoretical maritime law and practical security challenges, offering clarity and actionable insights for safer and legally compliant maritime operations. The book will be of interest to researchers in the field of maritime law, maritime security and the law of the sea.