||marine ecosystem (Pan et al. 2010, Sumardi et al. 2012). Currently, the only way to acquire frequent measurement is through remote sensing and conventional method is not practical and also costly. The current optical sensors which are widely used for Chl-a retrieval are Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer (MODIS). Both sensors has its own algorithm for Chl-a retrieval which are OC4v4 for global SeaWiFS and OC3M for global MODIS. Global algorithm do not always provide reasonable retrievals in all areas of the ocean, especially in coastal region due to the influence of suspended sediment, gelbstoff or yellow substance, river discharge and coastal pollution from land which gives overestimation of Chl-a concentration. According to Pan et al. (2010), an empirical algorithm depends on how good the data and on how representative the data are of the environment or bio-optical provinces where the algorithm is to be applied. Past research in coastal region shows that revised or new algorithm is needed for reasonable retrieval of Chl-a. Therefore, this study is done to determine the performance of current global algorithm and to modify the global algorithm so that it can achieve immediate applicability of Chl-a retrieval in the coastal region. This study focuses on the on the Pahang coastal region in east Peninsular Malaysia.