Chapter 3 covers the basic aspects of optical oceanography and ocean optics. This cross-disciplinary science includes the following topics: (1) electromagnetic wave propagation, (2) the nature of light, (3) radiometric terms, (4) radiative transfer theory, (5) inherent and apparent optical properties, (6) the identity and characteristics of marine absorbers and scatterers, (7) bio-optical models of primary production, (8) ocean colour, (9) underwater visibility, (10) remote sensing, and (11) atmospheric corrections for remote sensing. The material presented is an analytical review of numerical data and results, which are rearranged in context with remote sensing of ocean hydrodynamics. The chapter offers more insight into the subject than others literature sources. Light propagation and transmission in ocean and atmosphere are described by fundamental electromagnetic wave theory based on the Maxwell's equations and radiative transfer. In advanced concept, ocean and atmosphere both are defined as non-uniform media with stochastic properties. Optical properties are associated with internal inhomogeneities resulting to random fluctuations of the refractive index. In ocean water, those are caused by variations of density, temperature, salinity as well the influence of marine bio-particles and sediments. In the atmosphere, air motions, wind, aerosol scattering, and absorption are the main causes of optical turbulence and variations of light intensity. Interaction of light with the ocean, sunlight reflection, propagation, and scattering are key issues in optical remote sensing of ocean hydrodynamics. The atmosphere plays an important role in light propagation and formation of ocean optical images. Atmospheric turbulence reduces the azimuth resolution and the overall image resolution. Readers are encouraged to examine the references cited in this chapter.