An interactive A-level geography simulation exploring how El Niño changes precipitation across the Pacific and influences the water cycle around the world. Three linked views connect the physical mechanism to its consequences. Pacific mechanism shows changing trade winds, warm-water distribution, upwelling and the eastward shift of rising moist air and rainfall. Regional water cycle compares neutral conditions with developing El Niño across Australia and Indonesia, the central/eastern Pacific, coastal Ecuador and northern Peru, and northern South America. Global connections explores contrasting seasonal rainfall tendencies through an interactive map. Students can animate the transition, adjust the development slider, pause the action and hide process labels to explain what they observe. Rainforest vegetation gradually browns as western conditions become drier, with possible wildfire effects illustrating a further consequence of reduced precipitation. Designed for teacher demonstration, guided exploration and revision, the simulation helps students build explanations linking atmospheric circulation, precipitation, soil moisture, runoff and water availability. simopsis