To understand the complexity of the global methane cycle with its relation to climate change, it is necessary to identify relevant methane sources and to assess their environmental functions. The contribution of the various marine methane sources to the global cycle is only poorly understood so far. Methods are needed to survey efficiently methane release from the sea floor. This paper covers methane plumes from three different marine environments: methane release from gassy sediments in Eckernforde Bay, Western Baltic Sea; methane plumes above North Sea oil fields, and large plume above Hakon Mosby mud volcano, Western Barents Sea.