Preventing hypothermia in or near a waterfall requires managing "conductive" and "evaporative" heat loss. Even in summer, waterfall spray and the "wind" created by falling water can rapidly cool the body. You should avoid wearing cotton, as it holds water against the skin and loses all insulating properties when wet ("cotton kills"). Instead, wear synthetic or wool base layers that wick moisture away. If you plan to swim or stand under the falls, a wetsuit or neoprene top is essential to provide a thermal barrier. Limit your immersion time to short intervals, and have a dry towel and a complete change of clothes immediately available in a waterproof bag. The most critical step is to shield yourself from the wind as soon as you exit the water, as the combination of wet skin and moving air is the fastest way to drop your core temperature. Eating high-energy snacks like nuts or chocolate before and after can also help your body generate "metabolic heat" to stay warm.