Plan de Phazy

Plan de Phazy is a natural hot spring sitting at around 900 m altitude, straddling the border between Risoul and Guillestre, in the Guil valley in the Hautes-Alpes. It's one of the rare places in France where you can step into warm, mineral-rich water straight from nature, free of charge, surrounded by forest and rock stained with a distinctive rust-red hue.

Where does the hot water come from?

The water at Phazy travels up through the Durance fault from a depth of over 1,000 metres, reaching the surface at a steady 26 to 28°C regardless of the season. Along the way it picks up iron oxide, silicon, calcium, magnesium, chlorides and sulphates, giving it a mineral profile and staining the surrounding rock and marble a reddish-pink color. Today the spring emerges from pink marble and flows into four pools built in the 1980s, open to anyone year-round.

What's the history behind it?

The source was likely already used in antiquity, and in the Middle Ages it's thought to have served patients from hospitals operating in the Guil valley — the water was regarded as almost sacred. In 1824, at the tail end of Louis XVIII's reign and the start of Charles X's, a building known as La Rotonde was constructed right at the spot where the water surfaced, operating as a commercial spa and cure facility. The site changed shape in 1935, when an earthquake shifted the spring several metres, pushing it to emerge outside the building altogether.

What is the water known for?

The waters of Plan de Phazy have long been credited with therapeutic properties — traditionally used for eczema, arthritis, skin conditions, as well as rheumatic, liver and kidney complaints. No formal spa operates here anymore, but soaking in naturally warm water year-round remains the main draw for both visitors and locals, including in winter, when the contrast between snow and the warm pools is at its most striking.

How to get there and when to visit?

A short walk through the woods near the village of Guillestre leads to the springs, roughly between the town and the Risoul ski resort. The area falls within a protected Natura 2000 zone, making it worth visiting for the surrounding nature as much as for the pools themselves. The site is accessible all year, and a visit pairs well with a longer walk through the Guil valley. In summer, arriving early morning or late afternoon helps you avoid crowds; in winter, the combination of hot water and snowy scenery is what makes the spot memorable.

Frequently asked questions

Is entry to Plan de Phazy free? Yes, access to the pools is completely free and available year-round.

What temperature is the water? The spring water emerges at 26 to 28°C, staying warm regardless of the season.

How do you reach the springs? A short walk through the forest, between Guillestre and Risoul in the Guil valley, gets you there.

Can you bathe there in winter? Yes, the pools are open all year — a winter soak in warm water with snow all around is one of the site's main draws.