This chapter considers the adverse effects on marine biodiversity from the exploration for, and exploitation of, oil and gas in the marine environment. Reference is made to the Montara and Deepwater Horizon accidents. It is argued that if appropriate environmental law tools are not applied at appropriate stages, then environmental damage will likely ensue, raising issues of liability and reparation for environmental damage. Currently, there is no convention or fund related to civil liability arising from pollution by offshore oil and gas exploration and exploitation. There is also no global international convention devoted to the governance of marine installations. The chapter canvasses the history of the development of draft international legal regimes – and the adoption of various relevant, but non-specific, international legal instruments found in the law of the sea, in maritime law and in general environmental law instruments. The ‘Offshore Protocol’ to the Convention for the Protection of the Marine Environment and the Coastal Region of the Mediterranean 1976 (the ‘Barcelona Convention’) is considered as a possible turning point as the first instrument integrally devoted to the subject. In the conclusion the argument is made that the development of a new convention to deal specifically with the exploration for, and exploitation of, marine oil and gas would be valuable.