Fervedouro do Rio Sono, located in the Jalapão region near Mateiros in the state of Tocantins, Brazil, is a natural spring pool fed by multiple underground sources. Visitors can enter the clear water, float effortlessly due to the strong upward pressure, and relax while surrounded by dense vegetation. The pool has a distinctive shape and is accessed by a wooden platform, with limited capacity to preserve the environment. Nearby facilities include a restaurant and resting areas, making it a convenient stop during regional tours.