Since pure water is only penetrable by electromagnetic radiation in the UV Vis, you would have to choose a sensors sensitive in the wavelength range 300 - 700 nm. As most of the radiation measured by a satellite sensor is radiation scattered by the atmosphere, you require a very good calibration and a sophisticated atmospheric correction. The latter is much easier if you have several spectral channels allowing for a good estimate of aerosol and water vapour content. UAV and airborne instruments might be better suited, as the impact of the atmosphere is smaller due to a smaller distance of the sensor from the water surface (thus less atmospheric contribution to the measured signal). Active sensors (LIDAR) have been proven effective as well for this kind of application.