4. Rio Azul – Argentina

Hidden in Argentina’s Patagonian wilderness, Rio Azul lives up to its name with brilliantly blue, glacier-fed waters. While the river is cold year-round, braving the chill is worth it for the breathtaking clarity and purity. Surrounded by rugged landscapes, it feels like swimming through a watercolor painting. Whether you wade along the edges or take a full plunge, Rio Azul is an unforgettable stop for adventurous travelers.