In Chapter 2, basic principles of ocean hydrodynamics are considered. The chapter provides primary knowledge in fluid dynamics and ocean physics that is necessary for the understanding of remotely sensed data. Ocean hydrodynamics (OHD) plays a dominant role in the development of nonacoustic detection technology and environmental monitoring as well. Specifically, OHD investigations can be branched on several following parts: (1) dynamics of ocean waves, (2) ocean turbulence, (3) interactions phenomena, and (4) event-induced hydrodynamic impacts. Various studies, models, and data collected by many authors during the years are summarized and analyzed. This creates the OHD background framework for enhanced remote sensing. To illustrate progress in addressing and solving fundamental problems involving OHD, typical examples and dependencies are presented. An extended list of references provides comprehensive knowledge of the existing data and results. Their analysis has shown that a number of problems may require more attention in order to make determinative description of complex OHD processes and events. In particular, nonlinearity, randomization, and fractionation in the OHD environment should be considered in more detail. A possible “low-cost” solution is direct numerical modeling and simulations of OHD using computational fluid dynamics (CFD). It is believed that 3-D CFD are capable of providing comprehensive theoretical research and prediction of sophisticated OHD data and signatures that is necessary for advanced developments and applications.