The dynamic behavior of pipelines describes the time-varying continuous response of these structures under extreme effects, that are generated by the surrounding environment (waves and sea currents) and motions imposed by the host floating facility. This book describes all known impacts that affect the behavior and operation of a pipeline conveying an inner flow for underwater applications. "Known Impacts" are those phenomena that are considered important according to practice and experience. Underwater pipelines are typical, unique structures that are attached to unique floating facilities. The design and utilization of underwater pipelines depend strongly on the installation site and the intended application's particulars. It is possible that future technology demands will require us to cope with additional challenges that will be considered important for the design and operation of underwater pipelines, leading inevitably to the enhancement of the "known challenges".