Best Onsen and Spa Hotels Near Oiso
Hotels tagged spa-wellness near Oiso Long Beach lean on Kanagawa's hot-spring tradition rather than a chlorinated pool deck: open-air baths, indoor bathhouses and the odd rooftop soak sit a short drive from the bay. Oiso Prince Hotel keeps a spa and outdoor pool a few minutes' walk from the beach itself, while Tenseien Annex and Hadano Yugawara Onsen Manyo-no-Yu go further inland into the hot-spring valleys around Odawara and Hadano, where indoor and open-air pools sit side by side for cooler evenings. THE HOURS and MARSOL C.S.Beach hotel round out the group with a sauna each, one right on the coast. Expect a slower, bathing-first pace rather than a splash-park day.
Oiso and the hills behind it have drawn hot-spring bathers since long before the beach became a resort, and that layered history still shapes the group: Tenseien Annex and Hadano Yugawara Onsen Manyo-no-Yu sit in genuine onsen valleys, their bathhouses built around natural spring water rather than a heated tank. Oiso Prince Hotel is the odd one out, a bayside resort that pairs its spa with direct beach access. The result is a spa scene split between mountain onsen and coastal wellness, both a manageable taxi ride from Odawara Station.
Spa & Wellness · Oiso Long Beach in numbers
Where to stay
Onsen Valleys Behind the Bay
Why base a Kanagawa stay around onsen and spa rather than a beach-day hotel? Because Sagami Bay's coastline gets genuinely cold outside midsummer, and an open-air bath is what actually gets used most evenings of the trip. Every hotel in this group has a tagged bathhouse, sauna or spa, so the wellness side of the stay is never a maybe — it's the reason to book here over a plain business hotel by the station.
Tenseien Annex sits an easy walk from Odawara Castle in a genuine hot-spring valley, its bathhouse running both an indoor pool and an open-air bath alongside private-bath options for families who'd rather not share. The 4-star property pairs that with a restaurant serving its own kaiseki-style dinners, which matters here because the onsen towns around Odawara close early and taxis back from town can be slow after dark. Guests who plan an evening bath around dinner, rather than after a long day out, get the most from a stay built around bathing rather than sightseeing.
Hadano Yugawara Onsen Manyo-no-Yu goes a step further into the hills, a riverfront hot-spring hotel with mountain views and a bathhouse that runs an open-air bath, a private bath and a sauna side by side. Free parking and a free transfer service matter more here than at coastal hotels, since the property sits well outside easy walking distance of a station — most guests arrive by car or by the hotel's own pickup. The trade-off for that distance is a genuinely quiet onsen setting, away from the bay's summer crowds.
Oiso Prince Hotel keeps the spa idea close to the water instead: a bayside resort a few minutes' walk from Oiso Long Beach, running its own outdoor pool, small water park and spa alongside an open-air bath and sauna. It's the pick for a family that wants beach access and a bath, not a full onsen retreat — breakfast, a bar and a restaurant are all on site, so the day can run from beach to pool to bath without a taxi in between. Paid parking is available for anyone driving down from Tokyo rather than arriving by train, and the 4-star rating puts it a notch above the plainer business hotels further along this list.
MARSOL C.S.Beach hotel and THE HOURS sit at opposite ends of the spa spectrum: MARSOL pairs a sauna with beach access and a kitchen in each room, useful for a longer coastal stay that self-caters between bath sessions, while THE HOURS is a business hotel near Hiratsuka with a sauna and a casual bar rather than a full onsen. Both suit a shorter, simpler wellness stop rather than the multi-night onsen-valley trips that Tenseien Annex or Hadano Yugawara Onsen Manyo-no-Yu are built for. Neither includes free parking, so factor that into the cost of a stay built around either property, and neither sits within easy walking distance of Odawara Castle if sightseeing is part of the plan.
A traveler's takeI booked Tenseien Annex for two nights on a trip built around the Odawara Castle grounds, and the open-air bath ended up being the better memory — my son, who complains about every museum, sat in the outdoor pool at the bathhouse for a full hour after we walked back from the castle. The private-bath option meant we didn't have to time our soak around other guests, which made the whole evening far less rushed than I expected.
Spa & WellnessMARSOL C.S.Beach hotel
Check availabilityWhy guests love itWe brought our dog along mostly because MARSOL C.S.Beach hotel made it easy — the kitchen meant dinner didn't depend on finding a restaurant that would seat her, and the short walk to the water became her favourite part of the day, well ahead of the beach crowds that built up by mid-morning. The sauna in the evening was our own small reward once she'd settled down for the night.
Spa & WellnessOiso Prince Hotel
Check availabilityWhy guests love itThe pool became the fallback plan on our one grey afternoon at Oiso, and it worked better than expected — our five-year-old barely noticed the sea was too choppy to swim in once the water park's shallow end was an option instead. The open-air bath that evening was the adults' reward, a short walk from the room with the sea audible just past the treeline.
Spa & WellnessTenseien Annex
Check availabilityWhy guests love itWe chose Tenseien Annex mainly for the walk to Odawara Castle, and it was the private bath that ended up being the highlight — booking a slot at check-in meant we had the open-air pool to ourselves for a full half hour, no waiting for other guests to clear out after a long afternoon at the castle grounds. The on-site restaurant that evening meant we didn't have to head back out into town for dinner.
Spa & WellnessHadano Yugawara Onsen Manyo-no-Yu
Check availabilityWhy guests love itWe drove up specifically for the free parking and transfer after a week of city-centre Tokyo hotels charging for every extra, and the mountain view from the bathhouse turned out to be worth the detour on its own — soaking in the open-air bath at dusk, with the river below and no other coastal hotel's crowd noise, felt like a different trip entirely.
Spa & WellnessＴＨＥ ＨＯＵＲＳ
Check availabilityWhy guests love itWe stumbled onto ＴＨＥ ＨＯＵＲＳ after a long day of travel and mostly wanted the sauna, which turned out to be exactly what the trip needed — a quiet half hour before the bar downstairs, low-key enough that it felt like a genuine break rather than another item on the itinerary to check off before bed, no plans and nowhere else to be.
Local tips
- 1Book the onsen ryokan a season ahead if you're travelling during Japanese school holidays — Kanagawa's hot-spring valleys fill up fast once Tokyo families start planning weekend trips.
- 2Ask about private-bath slots when you check in; Tenseien Annex and Hadano Yugawara Onsen Manyo-no-Yu both offer them and they go quickly on busy evenings.
- 3Pack proper walking shoes if you're staying in the Odawara hills — the onsen valleys sit on sloped ground and the walk from parking can be steeper than it looks on a map.
- 4Time your evening bath after dinner rather than before; most of these hot-spring restaurants close earlier than a typical hotel kitchen would.
- 5If beach access matters as much as the bath, put Oiso Prince Hotel first — it's the only property in this group within walking distance of Oiso Long Beach.
- 6Confirm whether parking is free before you drive in; Hadano Yugawara Onsen Manyo-no-Yu includes it, but several coastal properties in this group charge for a space.