Open-air outdoor bath
Dry heat sauna room
Cold water plunge bath, typically used after sauna
Uses natural hot spring water
Free-flowing water, not recirculated
Private bath available for day-use visitors or hotel guests to reserve
Private onsen bath in guest rooms — for overnight guests only
Shared bathing area for all genders
Allows entry with visible tattoos
Restaurant or dining open to visitors (not just hotel meal plans)
Shower, wash stations, soap and shampoo provided
Towels available to rent or borrow
Relaxation space for after bathing
On-site or nearby parking available
Free
183. Tenzan Onsen, Hakone A top-tier onsen in Hakone that needs no introduction. Admission is 1450. Essentially a super sento in a beautifully maintained old ryokan building. The day I visited was very rainy and there weren't many visitors in the evening. The result was a spectacular atmosphere in the bath area: cooling rain, perfectly done evening lighting, great company, beautiful bath aesthetics. Basically, by the time I reached the changing room and saw the baths, I had zero questions about why this onsen is so highly regarded. Baths: 1. Large rectangular wooden bath. Clear water, temperature around 42-43. 2. Corner bath nearby with clear water, just warm temperature. 3. Main large stone bath. Temperature around 40. 4. Additional section next to the large bath, temperature around 44-45. 5. Two mini-baths up the stairs. Temperature around 40. 6. Steam bath in a small house. 7. Cold stone bath. Top-tier. When I'm back in Hakone doing another onsen run, I'll definitely go to Tenzan again.