The variety of morphological types of gas manifestation from the sea bottom and their different interpretations as to origin and terminology are considered. Similar to the transfer of thermal energy from the depths in the form of scattered (conductive) or concentrated (convective) flows, two types of gas flowsDegassinggas flows have been identified. Scattered gas flow is mainly dispersed over the area and has a largely biochemical origin, being formed by bacterial transformation of organic matter. Concentrated gas has mainly a thermogenic origin. It forms reservoirs by flows moving upwards from deep Earth. The most common example of thermogenic gas manifestations in the Black Sea are jets, or cold seeps. On their composition, size, and functionality, they are similar to those in other areas of the World Ocean. The number of discovered gas seeps in the Black Sea reaches 5000. Gas emissions from mud volcanoes are also described. A new type of underwater mud volcano is described, in which the channels of movement of mud volcanic material do not reach the sea bottom but die out in the sedimentary sequence. A review of chemical and isotopic compositionisotopic compositionof gas seeps along with regularities of their distribution in the Black Sea is presented.