The disposal of nuclear waste in the Sea of Japan is a complex and controversial issue where it involves aspects of international law and the international environment. Japan, as one of the largest nuclear waste-producing countries, has faced pressure to manage that waste in a way that complies with international legal principles and environmental norms. International law, such as the United Nations Convention on the Law of the Sea (UNCLOS), provides a framework for the management of marine resources, including waste disposal issues. However, the lack of clarity in international regulations regarding nuclear waste creates challenges in determining the limits of state responsibility and obligations. From an international environmental perspective, nuclear waste disposal can have long-term detrimental impacts on marine ecosystems and human health. Sustainability and sustainability of marine ecology must be a primary consideration in decisions regarding nuclear waste disposal. Meanwhile, various international conventions and agreements such as the Espoo Convention and the Aarhus Convention emphasize the importance of public participation in environmental decision-making. Therefore, the involvement of civil society in the decision process regarding the disposal of nuclear waste in the Sea of Japan is essential to ensure representation of public interests and concerns. This research aims to find out and analyze Japan's actions in dumping nuclear waste into the Pacific Ocean. The problem formulation in this research is: what is the role of UNCLOS 1982 in maintaining and protecting the international marine environment? This research was written using the normative juridical research type, which includes examining legal conflicts, legal vacancies, or vague norms.