Abstract: An inverse analysis for the estimation of internal sources in natural waters, using remote sensing data, is presented. The analisis involves a forward model that utlizes an analytical discrete-ordinates method for solving the radiative transfer equation, and an inverse model which contains an algorithm for least squares estimation that is iteratively solved for retrieving the desired optical properties by using the Levenberg-Marquardt optimizer. The experimental data are simulated with synthetic data (exit radiances) that are calculated at the surface of the water and corrupted with noise. The results show that the internal sources can be recovered with good accuracy, even for high noisy data.