This study aims to demonstrate how the accommodation of two different traditions in term of ideology and social that can be create tolerance and peace in society. A primary issue of this study is how the ideology and social accommodation take place between Islamic tradition and Osing.It is comprised in this research questions:1.How does the Islamic Tradition in the coastal of Kedungrejo village?2. How is the development of culture and tradition of Osing in Kedungrejo village? 3. How is the development of accommodation, tradition and ideology among fishermen in Kedungrejo village which will be the frame of cosmology?This study shows that ideology is a significant problem for the coastal societyare easily ignited emotions, misinterpretation and and do something fatal.However, coastal society generally known as a rampart and open minded  society, still permissive to the diversity of religions and ideologies.The attitude that always wanted to show the 'personal identity' is the one characteristic of coastal society.Osing as original tradition in Banyuwangi still provide color on fishermen appreciation for nature.So the accommodation between tradition and ideology bring forth cosmology of coastal societyin Kedungrejo village as a result of the accommodation between Islam and Osing become the local ideology that able to reduce conflicts