The development of geoengineering applied to the oceans - fertilisation, trapping and geological storage of CO2 - has put two areas of international environmental law in tension: climate law and international law of the marine environment. This study aims to look at the role that international environmental law could or should play in the development of geoengineering. The discussions that have taken place on geoengineering in international fora are rich in lessons about these rights themselves and with regard to their effectiveness and efficiency. Thus, questions of ‘good governance’ emerge. It is therefore a question of presenting the various possibilities offered by international law to frame - even forbid - these new practices.