The optical properties of the water column have a significant influence on phytoplankton growth. In this work, we report selected optical property values of the waters of two regions in the southern Gulf of Mexico. Measurements of natural fluorescence and photosynthetically available radiation (PAR) were made during a multidisciplinary research cruise, enabling the subsequent calculation of the light extinction coefficient (k), compensation depth (Zc), critical depth (Zc), and compensation light intensity (Ec). The results revealed an interesting contrast between the two areas but also indicated the presence of optimal conditions for phytoplankton community growth and net primary production. These data, as reported here, could set the stage for the development of bio-optical models of light penetration, ocean color and primary productivity in the region, as well as for future analyses of organic carbon energy flow. However, many more studies are required to establish the possible seasonal variations in these parameters, which could be linked to the wide variability of the region.