Environmental communication is about the relationship between humans with nature and the surrounding environment. The appreciation for nature and environment will have an impact on the environment that give benefits to human welfare. On the other hand, if human treats nature arbitrarily, the environment can be a threat to human life. This is what Conservation International (CI) does in supporting Kaimana as a Regional Area of Water Conservation. This study aims to provide an overview of environmental communication activities by CI in Kaimana waters conservation area. This research uses a descriptive method with qualitative data obtained through observation and interview. Informants in this research are the leaders and staff of CI Kaimana The results showed that the environmental communication activities conducted by CI based on custom conservation, in an effort to educate, socialize and involve Kaimana society participation. Environmental communication through customary approaches, such as sinara. Through mass media, online media such as: website, instagram or youtube. Face-to-face communication, direct discussion with the society and visits to schools conducted by CI with all its limitations, especially in implementing events related to conservation activities.