Hakone Onsen: seventeen hot spring areas on one volcano, and why the numbers never agree

Hakone is not one hot spring town but a cluster of them, scattered across the slopes of a volcano. That is the first thing to understand, and it explains the second: almost every number about Hakone’s water depends on who counted, when, and where they drew the line. This page sets out how the place works using the town, its tourism association, Kanagawa prefecture’s hot springs research institute and the Japan Meteorological Agency, and puts their figures side by side rather than picking one. It does not rate any bath.

For spring types, pH and how to read the analysis sign, see the separate guide to onsen water types; for the notices about added water, heating, recirculation and chlorine, see the piece on kakenagashi.

Where it came from

The founding

The tourism association says Yumoto, the hot spring at the bottom of the valley, is “said to have opened in 738”, and elsewhere that it is said to have been found in the Nara period. A prefectural museum publication also says the history is said to begin with the discovery of Yumoto’s spring in 738. Official sources give no other founding story. It is a tradition, not a record.

The association gives each area its own story, also as tradition:

• Dōgashima — said to have been opened by the monk Musō Kokushi (1275–1351).
• Kiga — linked to a legend of Minamoto no Yoritomo in the Kamakura period.
• Miyanoshita — natural spring water first found in 1398. The association also tells, as a legend and not a fact, that Toyotomi Hideyoshi bathed in a rock bath there during his siege of Odawara.
• Ashinoyu — in 1662 a man named Katsumata Seizaemon reclaimed a marsh, and the site of a pond became the basis of the spring. The association adds that in 2015 Ashinoyu became the first place in Kanagawa designated a national health resort hot spring (kokumin hoyō onsenchi).

From cure to resort

The town’s local history museum says that in the Edo period Hakone had seven hot spring areas, and that bathing was at first tōji, a stay for treating illness or injury. As writers made the scenery and temples known and travel such as the Ise pilgrimage grew, the springs came to be used for sightseeing and overnight stays too. The town’s history page adds that early in the Edo period the Tōkaidō road was laid from Yumoto by way of Hatajuku, with a checkpoint by Lake Ashi, and that in the late Edo period an overnight version of the cure, the “one-night tōji”, spread among travellers, with pilgrim groups bound for Ise and Mount Fuji. JNTO notes Hakone was an important rest stop on the Tōkaidō in the Edo period. The prefectural institute names the seven as Yumoto, Tōnosawa, Miyanoshita, Dōgashima, Sokokura, Kiga and Ashinoyu. A guidebook to them, the Shichitō no Shiori, was published in 1811; the tourism association and a prefectural museum publication both describe it as introducing each of the seven areas. The town museum’s permanent display, centred on hot springs and roads, follows the story from the seven of the Edo period to the seventeen of today. No official source dates the name “seven springs” more precisely than the Edo period.

After the Meiji era, the town says, Hakone became a summer retreat that foreigners also loved, and villas were built; in the Taishō era the Hakone Tozan Railway reached Gōra from Yumoto. The tourism association’s chronology records that Gōra joined the list of hot spring areas in 1919 with the opening of the Hakone Tozan Railway, that the first successful drilling in Gōra was in 1952, and that Takogawa, in 1993, is the newest of the seventeen. The present town of Hakone was formed by a merger in September 1956.

The prefectural institute adds that from Meiji on, better transport and better drilling and pumping made the number of sources rise sharply, and the springs began to run dry; it says the prefecture’s protection measures have slowed this.

The water

Seventeen areas, or twenty

The tourism association calls the whole the Hakone Jūnana-yu, “seventeen springs”: Yumoto, Tōnosawa, Ōhiradai, Miyanoshita, Dōgashima, Kiga, Sokokura, Ninotaira, Kowakudani, Gōra, Miyagino, Sengokuhara, Ubako, Ashinoyu, Yunohanazawa, Takogawa and Ashinoko. It groups them for visitors into five areas: Yumoto, Tōnosawa and Hatajuku; Miyanoshita, Kowakudani and Ōhiradai; Gōra, Miyagino and Kiga; Sengokuhara; and Ashinoko and Ashinoyu.

The prefectural institute defines Hakone Onsen as the hot springs that rise within the town of Hakone, and says that with twenty areas now it is called the Hakone Nijū-yu, “twenty springs”. Its list of the twenty is given as an image and is not reproduced here. So two official bodies use two different counts for the same place.

How much water: the figures side by side

Source	Figures	As of
Tourism association	25,000 tonnes a day from the seventeen areas; fifth in Japan (the measure is not stated); about 20 spring types	No date given
Prefectural institute	345 sources; about 19,500 L/min, nearly 60% of the prefecture; 48 spring types confirmed to date	End of March 2016
Prefectural institute, usage table	346 sources (250 in use, 96 not), 226 high-temperature sources, 18,069 L/min	End of March 2017
Same institute, elsewhere on the 2016 page	“Close to 350” sources	No date
Prefectural institute, citing the environment ministry	7th in Japan for sources and total flow, 5th for sources at 42°C or above, 1st for overnight guests (about 4.3 million), lodgings and capacity	2011 statistics
Prefectural museum publication, by an institute researcher	353 sources (616 in the prefecture); about 21,500 L/min; both about 57% of the prefecture	End of March 2012
Institute research report No. 43	353 sources, including those not in use	2011

The two older files are PDFs; only their legible figures are used here. The 2017 table notes that its source count excludes springs that have run dry or are suspended, and the tourism association calls its whole the seventeen areas while the institute counts everything in the town. The association’s daily tonnes and the institute’s litres per minute are in different units, and neither says whether they come from the same survey or year, so they are not converted here. Read in date order, the prefecture’s documents give 353 sources and about 21,500 L/min (2011–2012), 345 and about 19,500 L/min (2016), then 346 and 18,069 L/min (2017), and they may count differently. Official sources do not explain how the other pages count sources or why the figures changed, and the environment ministry’s published tables, being by prefecture, give no Hakone figure; the 2017 figure is the most recent official Hakone count available.

Spring types

The tourism association says about 20 types. The prefectural institute says 48 have been confirmed to date, the commonest being simple springs (including alkaline simple springs) at about half, then sodium chloride springs at about a quarter. An institute research report (No. 43) that analysed 257 sources in 2006–2008 appears to give 23, though only the figures in that file, not the text, are legible. The counts differ with what was surveyed. I do not choose one.

Why the water is like this

The prefectural institute says the heat and dissolved substances in Hakone’s water come from the hydrothermal activity of the Hakone volcano, and the water itself is rain and snow that fell on the volcano and soaked underground. It separates Hakone’s volcanic springs from the non-volcanic “fossil seawater” springs of Yokohama and Kawasaki, which the separate Honshu hot springs guide explains.

Within Hakone, the institute says, the water is not uniform. Sodium chloride springs are concentrated along the Sukumo river in Yumoto and inside a buried caldera at Gōra. Water with enough sulphur to count as a therapeutic sulphur spring is found only on and around the central cones. A separate institute page says acidic calcium sulphate springs rise around steaming ground such as Owakudani. The tourism association makes the same point with an image: Hakone’s springs are like a department store, with different water on different floors.

The Japan Meteorological Agency describes Hakone as a caldera volcano, about 8 km east to west and 12 km north to south, with active steaming ground at Owakudani and Sōunzan on the north side of the main peak, Kamiyama. It records no eruptions in historical documents, but has observed increases in steaming, landslides and debris flows, and swarms of earthquakes.

Owakudani

Owakudani is the steaming valley behind the black eggs; the tourism association records that hot water was piped from it to Sengokuhara in 1736. Its origin is described in slightly different ways.

• The meteorological agency: about 3,200 years ago a magmatic eruption of Kamiyama caused its north side to collapse, forming Kanmurigatake and damming the Haya river so that Lake Ashi took its present shape; a steam explosion followed about 3,000 years ago.
• Hakone Geopark: about 3,000 years ago the north side of Kamiyama collapsed on a large scale, and the steaming ground inside the collapse is Owakudani.
• The company that runs the Owakudani egg shop: about 3,000 years ago a steam explosion caused a landslide.

So “about 3,000 to 3,200 years ago”, depending on the source. The geopark adds that the valley was once called Ō-jigoku, “great hell”, and was renamed Owakudani after an imperial visit in 1873; that its hot water has been used since the Meiji era, with a full supply business from 1933; and that plants tolerant of volcanic gas and acidic soil grow there.

The town also runs its own hot water supply, to Ashinoyu, most of Motohakone and the Hakone district, through its water and onsen department.

Owakudani now

As checked on 11 October 2026. This changes; check before you go.

• Alert level. The latest stated level is in the meteorological agency’s bulletin of 24 July 2025, which says the level 1 forecast continued (“keep in mind that it is an active volcano”). The same bulletin reports 69 earthquakes near the south of Lake Ashi from 20 to 23 July, with a maximum intensity of 2 in places including Yumoto; says vigorous steaming has continued at Owakudani since 2015, active in part of the expected crater area; and warns that small ejections could occur without notice. The agency’s list of its Hakone information gives the most recent warning or forecast as the forecast of 7 October 2019 that lifted the warning. Its data on eruption warnings in force, fetched on 11 October 2026, has no entry for Hakone. That suggests no warning was in force, but no 2026 page states the level, so the 2025 bulletin is given with its date.
• The research institute’s view. Its statement dated 9 October 2026 says activity is broadly normal. It notes earthquakes rose briefly around 3 June 2026, that the make-up of volcanic gas had been changing since early June 2026, and that earthquakes in the last 30 days were small, the largest magnitude 0.8 on 8 October.
• It has closed before. The town records that on 7 October 2019 the level went from 2 to 1 and visitors were let back into the Owakudani area on 15 November, and that an entry restriction from 6 July 2022 was lifted when gas levels fell. The local volcano disaster council revised Owakudani’s evacuation plan and its alert levels in March 2025, the agency says; the details are not covered here.
• The nature trail. Kanagawa prefecture says the trail of about 700 m closed after the 2015 activity and reopened on 28 March 2022 for guided entry only: book in advance online, two monitors, about 40 minutes, four times a day, up to 30 people, primary school age and above, helmets on, no one with respiratory or heart conditions. Tours stop on days when gas exceeds the standard or the weather is bad. The prefecture monitors hydrogen sulphide and sulphur dioxide around the clock and asks people with asthma, other respiratory conditions or pacemakers not to visit.
• Booking. The tourism association’s booking page lists four slots, 10:00, 11:30, 13:00 and 14:30, finally confirmed 30 minutes before. The fee, a contribution, is paid on the day at the Owakudani information centre by credit card or transit IC card, not cash; meet 20 minutes before the start. Neither the prefecture nor the association says whether the fee includes tax, so the amount is not given here. The page says the explanation is in Japanese only and asks that only people who understand Japanese apply.
• JNTO notes that the sulphur gas can be irritating on some days and suggests people with respiratory problems avoid the area.

Official sources give no real-time information on whether the whole Owakudani area, its parking or the ropeway are open; the prefecture says its page does not carry it.

Bathing there

The town’s tourism association runs a day-bathing feature listing nine facilities, but gives a price for only one, without saying whether tax is included. Prices are not reproduced here.

The town itself runs bathhouses. As checked on 11 October 2026:

• Yasaka-yu — 9:00–20:30, closed Thursdays and occasionally otherwise (town page updated 15 October 2025).
• Miyagino Onsen Kaikan — 10:00–21:00, last entry 20:00, closed Thursdays; it also has a paid rest room for two-hour stays (town page updated 13 July 2026).

Both pages list separate prices for adults, children and town residents. Miyagino’s page says the adult bathing charge includes ¥50 of bathing tax; Yasaka-yu’s page does not say whether its price does. Neither page says whether consumption tax is included, so the prices are not reproduced here; check the town’s pages before you go.

The bathing tax. Hakone town levies an nyūtō-zei, a bathing tax, of ¥150 per person per night for overnight guests and ¥50 per person for day visitors (town page updated 30 March 2026). Children under 12, users of shared baths or ordinary public bathhouses, and pupils on school trips are among those exempt. The ¥50 in Miyagino’s adult price matches the day-visitor rate.

In English. No English page on bathing or tattoos is available from the tourism association, the town or the prefecture; the town’s English link goes to machine translation. JNTO’s Hakone spot page does not cover them. For general manners and the official position on tattoos, see the water types guide: policies differ by facility, so check in advance, and a private bath is an option where there is one. The tourism association’s information centre, a minute’s walk from Hakone-Yumoto station, is a JNTO-recognised centre with guidance in English (and Chinese and Korean, with those staff not always present), open 9:00–17:45.

What it is eaten with

Black eggs. The company that runs the Owakudani egg shop explains that raw eggs are boiled in a hot pool, using the chemistry of geothermal heat and volcanic gas, and the components of the pool stick to the shells and turn them black. It repeats the saying that eating one adds seven years to your life — as a saying. A bag of four was ¥500 including tax when checked on 10 October 2026. The tourism association lists “Owakudani’s black eggs” among Hakone’s souvenirs and says they can be bought at the Owakudani Kurotamago-kan, the geopark calls eggs made with the hot springs a speciality, and JNTO describes them in its Hakone itinerary. So the pairing of Hakone and black eggs appears on both the town side and the operator’s side.

Onsen manjū. The tourism association runs a feature on Hakone’s steamed buns, without explaining where onsen manjū came from. Its prices are from 2020 and not tax-inclusive, so they are not used here.

The farm ministry’s list of Kanagawa’s local dishes names one dish from Hakone, wakasagi no kanroni: smelt from Lake Ashi grilled and then simmered, glazed with starch syrup. The ministry’s page for the dish says the smelt eggs were brought from Kasumigaura in 1918, that net fishing opens each year on 1 October, and that in the season it is served at local ryokan and restaurants. It says inns, not hot springs, and the town side does not describe it, so this page does not call it Hakone’s onsen dish. More on Kanagawa’s dishes is in Kanto’s local dishes.

Getting there

As checked on 11 October 2026.

• From Shinjuku. Odakyu says the Romancecar limited express runs direct to Hakone-Yumoto in about 80 minutes; its global home page headlines 80 minutes from Tokyo by Romancecar and elsewhere puts Hakone about an hour and a half from central Tokyo. A limited-express ticket is needed on top of the fare. JNTO gives about 90 minutes by the Odakyu line, without saying which train.
• The Hakone Freepass. Odakyu sells a two-day and a three-day pass from Shinjuku. It covers eight kinds of transport in the Hakone area, including the railway, cable car, ropeway, buses and the sightseeing boats on Lake Ashi, and gives a discounted return between Shinjuku and Odawara. The Romancecar is not included; the limited-express ticket is extra.
• From Tokyo Station. JNTO’s spot page gives about 55 minutes by Tōkaidō shinkansen to Odawara and the Hakone Tozan line to Hakone-Yumoto. Its itinerary page gives 35 minutes to Odawara and 15 minutes on to Hakone-Yumoto by Romancecar, headed “50 minutes”. Two JNTO pages, two totals.

Odakyu’s pages do not say whether their prices include tax, so they are left out here; check them before you buy. This page gives no official time from Hakone-Yumoto on to Gōra, and the tourism association’s access page is images only.

What people get wrong

• “Hakone is one onsen town.” It is a cluster of areas spread over a volcano — seventeen by the tourism association’s count, twenty by the prefecture’s.
• “Hakone has X sources.” Every official figure comes with a year and a way of counting. The most recent prefectural figure available is 346, as of March 2017.
• “All Hakone water is the same.” The prefecture says sodium chloride water clusters at Yumoto and Gōra, sulphur water around the central cones, and acidic calcium sulphate water around steaming ground such as Owakudani.
• “Owakudani is a free walk.” The nature trail is guided entry only, booked in advance, with guidance in Japanese, and it stops when gas levels require.
• “Hakone’s founding date is 738.” That is the tradition the tourism association gives for Yumoto. Each area has its own story.
• “The black eggs make you live longer.” The operator gives the seven years as a saying, not a claim.