The marine environment is estimated to be one of the most significant sources of biological activity in the world. In the last few decades an increase in the research intensity conducted on marine microorganisms has been observed, which confirms the great potential of these organisms in the field of bioactive compounds' production. In order to efficiently use the natural resources of the marine environment, metagenomics can be applied. This powerful technique allows for efficient screening of microbial biodiversity for bioactive compounds. The primary aim of this review is to present some aspects of the construction of metagenomic libraries, and strategies of screening for novel bioactives in the marine surrounding. This paper also illustrates several examples of the application of metagenomic methods in the discovery of novel enzymes and drugs in various marine environments.