In this paper we review the current understanding of bubble plumes discharged from subsea sources related to oil and gas production, and show how CFD can be applied for risk assessments. A general introduction to causes and risks is given. This is followed by a discussion of the physics that need to be accounted for before giving a brief review of the different modelling approaches employed today. The empirical and experimental knowledge base is also summarized. An example of how CFD can be applied to study gas releases is given. At the end we outline what is needed to advance current understanding of such releases and model their interaction with the surroundings. The scope of the review is limited to the fate of the gas and the flow induced by the ascending bubble plume in the water column. Atmospheric dispersion of surfacing gas is not considered.