There is increasing demand for scientific knowledge about the marine environment and the profound influence that human activities are having as the predominant driver of change in the global ocean. However, while not necessarily the case, the conduct of MSR may also contribute to environmental damage. There are also concerns that research may give rise to new technologies or uses that pose environmental risks. This chapter examines the legal regime for MSR in Part XIII of the LOSC and its progressive development with a view to understanding its relationship to the regime for the protection and preservation of the marine environment in Part XII, as well as other provisions in the LOSC. In many respects, these parts are mutually reinforcing in requiring that states promote, facilitate and cooperate in MSR to support the production of information necessary for effective environmental regulation and management. Nonetheless, a state can justify certain restrictive measures aimed at environmental protection, even if such measures limit the conduct of MSR, where such restrictions are necessary and reasonable. An important development is the specification of best practices for carrying out MSR in other instruments in accordance with the general principle in Article 240(b) of the LOSC to use appropriate methods and means. Another form of ‘best practice’ relates to transparency and the duties of States to publish and disseminate research results, data and scientific information to maximise the societal benefits of MSR. The chapter also surveys the implications of the zonal approach for the conduct of MSR and environmental information gathering activities, the provisions on scientific research equipment and installations, issues related to legal responsibility and liability for damage caused to the marine environment from the conduct of MSR, and dispute settlement.