.The propagation of a vapor explosion- through a series of molten tin drops immersed in water has been investigated experimentally. Spontaneous explosions occur for single drops over a range of water and drop temperatures. After,a drop contacts the water, an explosion occurs after a delay time that increases with the drop size and water temperature. This delay time corresponds to the time required for the transition from film to nucleate boiling to occur spontaneously. In situations in which stable film boiling would otherwise occur (e.g., low water subcooling), collapse of the vapor film surrounding a drop and explosive boiling was triggered by the impact with a cold underwater jet and with the passing of a shock wave generated by the discharge of a high voltage capacitor across an underwater spark gap. The peak overpressure generated during the explosion of a single drop increases roughly linearly with drop mass. The scatter in the peak overpressure results also increases with drbp size due to variations in the drop shape resulting in varying amounts of tin which participates in the interaction. In an unconfined linear array of drops, spatial propagation of the explosion occurs when the shock wave and convective disturbance produced by the vapor explosion bubble dynamics from one drop trigger an adjacent drop,. The critical drop spacing required for propagation was determined as a function of water temperature for 2.5, gm drops. For drops spaced at or near the critical drop spacing, the shock wave generated by the collapse of the high pressure vapor bubble from one drop plays the dominant role in triggering the explosion of an adjacent drop. Through this propagation mechanism, the explosion front was observed to propagates at an average velocity of 5-10 m/sec. For closely-spaced drops, convective effects become important, and the flow disturbance generated by the expansion of a steam explosion bubble is sufficient to trigger a neighbouring drop. Marginally faster propagation velocities can be achieved by this mechanism.