There’s a reason it’s called Zao Onsen – and that’s because the region is one of the best for enjoying warm, calming onsen water. Almost all of the hotels and ryokans will have in-house onsens for men and women, some with more luxury than others but all fed with the same perfect water, and there are a number of public onsens in town for guests to the area to use. The water in these onsens is sourced from the volcanic mountains, heated and mineralized naturally and brought to the surface in these beautiful baths for guests to use to relax, unwind and experience tranquility. It was originally the onsens that attracted people to the area, hundreds of years ago, and many of the onsens around today are steeped in history. The water is strongly acidic and sulfuric, with anti-bacterial properties and supposedly great for smoothing skin and healing sore muscles.

If you’re looking at visiting the onsens, it may be worth buying an unlimited pass through the purchase of a traditional Kokeshi Doll from the tourist information center. This provides you with free access to a number (not all) of hotels' and public onsens throughout your stay.