||The interaction of round buoyant jets with water waves was studied experimentally by flow visualization techniques. The experiments were performed in a water tank equipped with a jet generating mechanism and a surface wave generator. The jets were driven by a constant head mechanism whereby the ejected water was pre-heated to a series of temperature differences from the ambient temperature of the tank water. The temperature profiles at various distances from the jet nozzle were measured by a thermistor scanned through the jet cross-section. Surface water waves were generated by a plunger-type wave maker. For this experiment, standing waves were produced at different frequencies to form nodes and antinodes above the jet. The wave amplitudes were measured by a capacitance wave height gage. Using potassium permanganate (KMnO4) as a dye tracer, the response of the buoyants jets to the wave motions was then monitored by video recording and analyzing systems. The jet diffusion angles measured from the jet axis to the tracer outline were determined from visualization to quantify the level of dilution. The present results indicated that a) the far field cross-sectional temperature distributions for the buoyant jet are Gaussian, b) the surface water waves have very strong diluting effects on the jet mixing, c) the jet mixing is enhanced by a stretching/compression mechanism for vertical oscillations (antinode) and by a deflection/looping mechanism for horizontal oscillations (node), and d) the degree of jet mixing depends strongly on the competing process of buoyant force and wave action which is qualified by a wave Richardson number.