This paper aims to describe the importance of environmental diplomacy in saving threatened marine ecosystems. The sea has unique physical characteristics to become a challenge of cooperation between countries in establishing a cooperation. This paper finds that the cooperation of the Indonesian government in implementing the CTI-CFF mandate is through cooperation, both cooperation between signatories and partner countries as well as cooperation with Non-Governmental Organization (NGO). This is done by Indonesia in order to contribute Indonesia in saving the threatened marine ecosystem.