Abstract This paper reports on an investigation how far raindrops with free fall terminal velocity can penetrate the mixed layer of the sea water. This issue is studied by preparing an experiment set for the different radii that raindrops have. How far the raindrops can move in the mixed layer is found to depend on their kinetic energy. The data obtained from the results of the experiment are compared with the data obtained from the proposed relation. Knowledge of the penetration depth of the raindrops is important to determine the changes in ocean heat and salt content.