Onsen, sento, super sento, outer baths — which should a traveller pick?

Four similar-sounding things, ranked from a traveller's point of view.

Definitions

Onsen — geothermal water as defined by the Onsen Law.

Sento (public bath) — neighbourhood baths for residents, usually heated tap water. Prices are capped per prefecture; ¥550 in Tokyo.

Super sento — large private complexes with multiple tubs, sauna, rock baths and restaurants. ¥1,000–2,500.

Outer bath (soto-yu) — public onsen bathhouses in resort towns. Kinosaki's seven and Nozawa's thirteen are the famous ones.

Ranked for travellers

1. Super sento and day-use onsen — no booking, towel rental, multilingual signs. Hardest to get wrong.
2. Outer baths in onsen towns — cheap and genuine. But expect no soap, very hot water and ¥10 coin lockers.
3. Day-use at ryokan — limited hours, often midday only.
4. Local sento — little English, regulars' etiquette. Choose only heritage buildings or places that state tattoos are OK.

Our policy

We focus on 1–3 and limit 4 to places that clear the 'a traveller won't struggle here' bar.