Zao Onsen

**Best onsen choice:** Zao has 30+ onsen options. For the quintessential experience, go to Dai-Rotenburo (大露天風呂), a large outdoor mixed-gender bath (swimsuits not allowed, as per Japanese onsen etiquette) located 10-min walk uphill from village center. The bath sits in a forest clearing surrounded by rocks and mountain views. The water is nearly opaque emerald-green and strongly sulfurous — immersion creates immediate tingling sensation on skin. The bath is rustic (changing rooms are basic wooden shacks) and authentic. Women concerned about mixed-gender bathing can visit during morning hours (6:00-8:00) when it's predominantly empty. **Sulfur intensity warning:** Zao's water is among Japan's most acidic. Do NOT enter if you have cuts, abrasions, or sensitive skin conditions — the acidity will cause significant stinging. Remove all metal jewelry before bathing (silver tarnishes within minutes). The smell of sulfur is overwhelming; your clothes and hair will retain the scent for 24-48 hours even after showering. **Ski + onsen combination:** In winter, the village offers a perfect daily rhythm: ski 8:30-15:00, return to village, soak in onsen 15:30-17:00, eat kaiseki dinner at ryokan 18:00. Many onsen ryokan have ski-in/ski-out access. Recommended: Takamiya Hotel (高見屋, onsen directly connected to ski slopes, ¥15,000/night including meals). Book 2+ months ahead for winter weekends. **Summer alternative advantages:** Zao Onsen in summer (May-October) is dramatically cheaper (ryokan rates 40% below winter), less crowded, and the onsen water is identical quality. Summer hiking around Mt. Zao offers alpine flowers and crater lake (Okama, お釜) visits. If your primary interest is onsen rather than skiing, summer is superior value and experience.