The stability of a steam plume during direct-contact condensation into a crossflow of subcooled water is investigated for mass fluxes that are higher (>600 kg/m2s) and a nozzle diameter (2.4 mm) that is smaller than typically seen in the literature. The transition from a stable steam plume to an unstable plume associated with the formation and collapse of steam bubbles is characterized by high-speed imaging and high-frequency pressure measurements. Four regimes are observed: stable, condensation oscillation, transition, and unstable. A regime map and spectral signatures of the different flow regimes are provided. Results are compared with correlations from the literature, which are typically derived for lower mass fluxes, larger nozzles, and injection into stagnant pools of water.