Free Hot Springs · Bagni San Filippo · Val d'Orcia
The thermal area of the Fosso Bianco is a generous one. The first pools you come across from the path, as you follow the stream uphill, hold clear and very warm water. Carry on along the trail beside the little river and you reach the White Whale waterfall — a vast block of limestone formed over centuries by the chalky, mineral-rich hot water, which mingles with the stream and lends it that characteristic milky blue-white hue, in striking contrast to the surrounding woodland.
The waterfall takes its name from its likeness to a whale's open mouth. It is the most arresting limestone formation at the Fosso Bianco, fed by the hottest water of all — the spring nearby rises at 48°C, warm enough for a bathe even in the depths of winter.
The volume and course of the water spilling over the cascade shift constantly, forever reshaping the scene with fresh forms and colours. In winter the thermal water mingles with rainfall, drawing out shades from green to a russet brown.
The waters of the Fosso Bianco are hyperthermal, rich in sulphur, sulphates, calcium and magnesium. The mud that forms naturally as these minerals settle is prized for its benefits to the skin.
Further down the valley, near the spa, the abundant waters of the pool are released into the Fosso Bianco, warming it further still.
The way in begins in the village of Bagni San Filippo. Follow the signs and you join a path that leads into the woods, accompanied by the murmur of thermal water over white pebbles. The first pools lie only a short distance from the entrance; to reach the White Whale, carry on for around ten minutes along the natural trail.
This is no manicured spa — it is nature, pure and simple. Over the years locals and visitors alike have built up small new pools from stones and branches; the lime-rich water sets quickly, forever creating fresh basins to bathe in.
Summer — the water runs cooler where it mixes with the stream; pools are plentiful but busy. Best enjoyed early morning or late afternoon.
Winter — the most magical of all: steam rising from the warm water, a hushed atmosphere and few visitors. The White Whale takes on quite different colours.
Spring and autumn — the ideal balance of water temperature, woodland colour and quiet.