The interaction of pulsed carbon dioxide laser radiation with the free surface of water gives rise to shock waves in the water and in the air above the surface. In addition a train of high‐frequency, ∼20 MHz, oscillations in the water have been observed using ultra‐high‐speed photography by means of a nitrogen laser with a pulse duration of ∼1 ns. Confirmation that the oscillations are not due to diffraction effects in the shadowgraphs has been obtained by direct pressure transducer measurements in the water.