Chlorophyll-a concentrations (mg/l) in surface waters of Songsong Islands were mapped using an optically derived remote sensing model. Landsat TM imagery dated 8 October 2008 was used in the classification process and in situ measurements made on 19 May 2012 during spring tidal condition (HW: 2.6 m, LW: 0.9 m) served as ground truthing data. The temporal difference between data used will be useful to review the robustness of the model. Three classes of chlorophyll-a concentrations were mapped: Class 1: 10 mg/l. Considering the dynamic nature of coastal and marine waters particularly the shallow region, and the temporal difference between the Landsat TM imagery used in classification and the field data, results of chlorophyll-a mapping using the developed remote sensing model was high at 83.3%, with producer’s accuracy of 50%–100% and user’s accuracy of 80%–100%. Kappa coefficient of agreement, Kˆ , calculated was 57.1%.