The paper includes a review of the main problems of the ocean optics. It gives information about history of hydro-optics, inherent optical properties (IOP) of the natural waters, methods of IOP measurements, and physical and empirical models which allow to find relations between different IOP. The methods of solving the radiation transfer equation for quantitative data on natural and artificial, including pulsed, underwater light fields are considered. The main concern is with the methods of remote sensing of the ocean which are the most promising in terms of practical implementation. These methods are: determination of the concentrations of optically active matters (phytoplankton, sediment and dissolved organic matter) from data of multi-spectral ocean sensing; retrieval of the depth distributions of IOP and detection of the inner waves by oceanic lidars; detection of oil films on the sea surface; observation of underwater objects and the sea bottom by imaging systems placed on the submerged vehicles, ships, planes and satellites. A simple optical model of maritime atmosphere needed for computing the airborne and satellite -based imaging systems is given. The effect of rough sea surface on underwater object visibility is considered, as well as methods of correction of the images, distorted by surface waves.