Situated in the eastern and northeastern regions and subjected to similar oceanic processes, the inshore waters north of 20¿N and east of 65¿E are more optically complex than the offshore waters and waters south of 20¿N and east of 65¿E. This has been observed through the analysis of variations of the remote sensing reflectance (Rrs(λ)) in the optical spectrum of Electromagnetic radiation. The optical complexity has further been studied through the examination of optically active substances (OAS) such as chlorophyll_a, suspended sediment and coloured dissolved organic matter (CDOM). It is found that CDOM is the significant component in making the area optically non-linear. For the first time multi-spatial/temporal band-ratio algorithms are developed to map OAS from these waters through Ocean Colour Monitor flown on IRS -- P4 satellite.