A detailed understanding of the vibrational properties of submerged objects such as submarines is essential in order to minimize sound emission and optimise sonar performance. In this work we present some results on the effect of water loading on a simple rigidly clamped plate. Complications arise when hollow structures are submerged in water producing loading on one side. Not only does the water dampen the resonances of the structure but the increase in depth also produces mechanical strain within the structure that also changes the modal frequencies. In this paper some results are presented on the effect of water loading on a simple rigidly clamped plate. The aim of this work is to accurately measure these effects and identify any interesting features that need to be taken into account when modelling.