This chapter identifies eight elements of the principle of common heritage of mankind (CHM) in the context of DSM, which exhibits a delicate balance between development and conservation. Environmental protection is an integral and inherent restrictive element of CHM. The chapter reflects preliminarily upon environmental protection in DSM at the conceptual and operational levels. At the conceptual level, it argues for an erga omnes character of international environmental obligations. Such a characterization would make a big room for innovative practices with respect to a more informative, inclusive and transparent model of global environmental governance of DSM as well as have legal implications on the question of who is entitled to invoke liability of the contractor, the sponsoring State and the ISA for environmental damage. At the operational level, it highlights the significant role of marine sciences and the fact that the great gaps of current marine scientific knowledge constitute a fundamental restraint to the development of DSM as well as the environmental protection in DSM.

This chapter recapitulates the main findings of the book. First, it rearticulates that the principle of CHM as the tenet for the DSM regime can stand against changes of circumstances as it reflects a trend of international law – community interests. Then, it explains the role each participant plays in the marine environmental protection in DSM. Thirdly, it highlights the role of marine sciences as well as the necessity to respond to its limitations. Fourthly, it clarifies international environmental obligations of participants. Especially, it highlights the fact that the ISA takes a leading role in applying the precautionary approach which is of particular importance in a context of scientific uncertainty of DSM’s impact on the marine environment. Fifthly, it synthesizes the establishment, content and implementation of liability of participants, and points out the practical difficulties in the application of liability regimes. Final observations about the future development of DSM regime are made in the end.