Best Saunas in Karuizawa, Japan
AQUAIGNIS GARDEN SPA
Station-side day spa at Karuizawa T-SITE with two Finnish-style sauna rooms, herb-infused indoor bathing and an outdoor bath. The operator sells public admission without a hotel stay. The sauna is for guests aged 13 and older, and final entry is one hour before closing.
Kaveri Private Outdoor Sauna
A separately bookable sauna in Oiwake with private wood-fired cabins, self-löyly, dedicated groundwater cold baths and forest-facing rest decks. The operator offers individual shared sessions as well as exclusive group bookings; neither requires an overnight stay. Swimwear is required.
Happu Onsen Day Spa
Separately ticketed day-use bathhouse at Le Grand Karuizawa Hotel & Resort. The venue offers hot-spring indoor and outdoor bathing plus a sauna and cold bath, and the operator says non-residents can enter without advance booking. Use the Happu Onsen reception, separate from the guest-only KOMOREBI bath.
Hoshino Onsen Tombo no Yu
A public day-use onsen in the Hoshino area, open regardless of whether visitors stay at the resort. Its sauna runs around 85–90°C with automatic steam every 20 minutes. The bathing area also has a spring-water cold bath and outdoor space for cooling down.
Karuizawa Sengataki Onsen
This Prince Hotels public hot-spring bathhouse includes a low-temperature Finnish cottage sauna and a hinoki cold bath, alongside indoor and open-air pools. Day tickets are sold to all visitors. Hours and admission prices vary between weekdays, weekends and designated peak dates.
AQUAIGNIS GARDEN SPA
Station-side day spa at Karuizawa T-SITE with two Finnish-style sauna rooms, herb-infused indoor bathing and an outdoor bath. The operator sells public admission without a hotel stay. The sauna is for guests aged 13 and older, and final entry is one hour before closing.
Kaveri Private Outdoor Sauna
A separately bookable sauna in Oiwake with private wood-fired cabins, self-löyly, dedicated groundwater cold baths and forest-facing rest decks. The operator offers individual shared sessions as well as exclusive group bookings; neither requires an overnight stay. Swimwear is required.
Happu Onsen Day Spa
Separately ticketed day-use bathhouse at Le Grand Karuizawa Hotel & Resort. The venue offers hot-spring indoor and outdoor bathing plus a sauna and cold bath, and the operator says non-residents can enter without advance booking. Use the Happu Onsen reception, separate from the guest-only KOMOREBI bath.
Hoshino Onsen Tombo no Yu
A public day-use onsen in the Hoshino area, open regardless of whether visitors stay at the resort. Its sauna runs around 85–90°C with automatic steam every 20 minutes. The bathing area also has a spring-water cold bath and outdoor space for cooling down.
Karuizawa Sengataki Onsen
This Prince Hotels public hot-spring bathhouse includes a low-temperature Finnish cottage sauna and a hinoki cold bath, alongside indoor and open-air pools. Day tickets are sold to all visitors. Hours and admission prices vary between weekdays, weekends and designated peak dates.