This episode highlights the critical role of rehydration in heat adaptation, focusing on how water, electrolytes, and carbohydrates support thermoregulation and performance. We discuss specific hydration strategies, including pre-, during-, and post-exposure protocols, and address challenges such as environmental and behavioral factors. The role of the kidneys, mediated by hormones like ADH and aldosterone, is explained in maintaining fluid balance. Tailored approaches for special populations, such as athletes, older adults, and children, are emphasized, alongside practical applications for sports, occupational settings, and recreational activities.