A study has been completed which undertook an examination of the state-of-the-art in pipeline leak detection technology. The advantages and disadvantages of currently available technology have been analyzed with special consideration given to the possible application in deepwater, subsea and arctic developments. These developments represent a significant departure from conventional production operations. Rather than pipelines transporting a processed and single-phase fluid, these developments flow a complex mixture of oil, water, and natural gas. Pipelines transporting an unprocessed, multiphase mixture will be termed flowlines in this study. These flowlines represents a special challenge for leak detection and one that has largely been ignored by both industry and regulators. While historically the number of shallow water releases from pipelines is extremely small, deepwater, subsea and arctic flowlines operate under conditions rarely encountered in previous development schemes. The remoteness of these flowlines, coupled with a number of complex interactions between the released fluids and the deepwater environment makes detection much more difficult. Leak detection using conventional methods is also made difficult by the reduced accuracy or complete lack of flow rate measurements at the flowline inlet. A key focus of the study was to quantify how currently available leak detection methods will function under multiphase flow conditions and what role multiphase metering can play in reducing risks. New methods, such as compositional monitoring and data-driven momentum balance methods were also investigated. The goal of this work has been to provide the information necessary for decision makers to develop strategies for the special testing, inspection and monitoring requirements of deepwater, subsea and arctic pipelines.