How Do You Stay Safe in Hakone? Volcano, Gas, Rain and Emergencies

Published 2026-10-04 · Sources checked 2026-10-04 · Treasure Hunting Co., Ltd.

This guide is for visitors to Hakone and for people who stay in holiday homes in the Hakone hills. It covers the volcano and its alert levels, volcanic gas at Owakudani, closures after heavy rain, hot bath safety and the emergency numbers 110 and 119.

We used pages from the Japan Meteorological Agency (JMA), Hakone Town, Kanagawa Prefecture, Kanagawa Prefectural Police, the Fire and Disaster Management Agency, the Hakone Town Tourist Association and Hakone Navi. All were read on 2026-10-04. In an emergency, follow local announcements and staff instructions first.

Hakone is an active volcano

Hakone Town points out that "Hakoneyama" is the name of a volcano. There is no single mountain with that name. JMA watches it all the time with seismometers, tiltmeters, GNSS, cameras and other instruments.

JMA's record of past activity includes these events:

• Three steam-driven eruptions near Owakudani, from the late 12th to the 13th century.
• A landslide at Soun-jigoku on 26 July 1953 that killed 10 people. JMA says its link to the volcano is unclear.
• A very small steam-driven eruption from 29 June to 1 July 2015, with new steam vents found.
• A rise in earthquakes and ground swelling in 2019.

The alert level on the day we checked

On 2026-10-04, JMA's status for Hakoneyama was Level 1, which means "be aware this is an active volcano". This forecast dates from 10:00 on 7 October 2019, when JMA lowered the level from 2 to 1. JMA had issued no new information in the previous week.

JMA's current cautions are short. Small bursts of material may happen suddenly, because Hakoneyama is an active volcano. In the area around Owakudani where a vent could open, steam vents are active, so watch for steam and volcanic gas.

In July 2025, JMA reported a series of earthquakes under the south of Lake Ashi. There were 69 earthquakes from 20 to 23 July, and the level stayed at 1. JMA's report for August 2026 said activity was generally quiet. It recorded steam rising up to 500 m at Owakudani. Its next monthly report was due on 8 October 2026.

Check the level yourself on JMA's page before you go. The level can change quickly.

What each level means in Hakone

Alert levels have applied to Hakoneyama since 31 March 2009. They were revised in March 2025 with a new hazard map. Hakone Town says the revision does not mean the danger has increased. JMA's leaflet for Hakoneyama sets out the response at each level:

• Level 1: entry into the area where a vent could open may be restricted, depending on conditions.
• Level 2: entry around that area is restricted. Marked roads and the ropeway cannot be used, though people can still enter and leave Ubako and Sounzan ropeway stations.
• Level 3: entry is restricted up to about 600 m from that area.
• Level 4: Hakone Town issues an evacuation order at this stage. The leaflet gives two reasons: the town must move very large numbers of visitors, and homes stand close to the possible vents.
• Level 5: evacuation from residential areas in danger.

The leaflet also marks "specific areas". These are closer to the possible vents than ordinary residential areas and include holiday homes. People there must leave earlier, at Level 3. Hakone Town says the 2025 revision added part of the Ubako district as a specific area. The district named under the old plan is no longer one.

Volcanic gas at Owakudani

Kanagawa Prefecture says volcanic gas comes out at Owakudani. People with asthma, bronchial or other breathing problems, heart disease or a pacemaker should not visit the Owakudani area. The prefecture says the gas can be life-threatening for them.

• Restricted zone. The area around Owakudani is a designated restricted zone. Prefectural Road 734 from the Owakudani junction to the Owakudani car park is open only from 9:00 to 17:00.
• Gas checks on the road. The prefecture's hot spring research institute measures gas near Owakudani Bridge. At 2 ppm of sulphur dioxide, Hakone Town gives warnings, for example over its disaster radio system. At 10 ppm, part of Road 734 is closed.
• The nature trail. The loop of about 700 m through the steam field reopened on 28 March 2022, by advance booking only. A walk takes about 40 minutes. Groups of up to 30 walk it with helmets and two safety staff, four times a day.
• Trail fee and language. Each walker pays an 800 yen safety fee on the day, by cashless payment only, such as a credit card or transport e-money. The tourist association says explanations are in Japanese, so apply only if you understand Japanese.

The Hakone Ropeway stops when gas levels rise, based on readings at several points. These readings are not directly linked to the alert level. Some hiking trails near Owakudani are closed, so check before you walk.

Heavy rain, wind and road closures

Hakone Town says ordinary roads in the town may close when rain reaches 200 mm since it began, or 50 mm in an hour. If ordinary roads close, route buses also stop. The ropeway may also stop for strong wind, lightning or an approaching typhoon.

The town points visitors to its Hakobo Map, a website with transport and disaster information. In a disaster, it shows which shelters are open. Hakone Navi shows the status of the trains, ropeway, boats and buses.

Hot baths

Hakone Town warns that accidents in the bath are increasing. Moving from a warm room to a cold changing room raises blood pressure. Hot water then lowers it, and sweating dries you out. These changes can make people faint, fall or drown.

Emergency numbers

• 110: police. Every 110 call in Kanagawa goes to the Kanagawa Prefectural Police command center in Yokohama. The call taker will ask what happened, when, and where.
• 119: ambulance. The Fire and Disaster Management Agency says to call 119 when you need an ambulance. The service is available to anyone in Japan.
• Keep your phone on. Hakone Town's fire department may call you back while the ambulance is on its way, to ask for details.

What we could not verify, and therefore left out

• Exactly which hiking sections near Owakudani are closed today. A Hakone Town page says the trail between Mount Komagatake and Mount Kami reopened on 28 March 2025. A Kanagawa Prefecture page updated in May 2026 lists a closed section of about 3 km. The two do not clearly match.
• Today's gas readings. The ropeway's gas display loads separately, and our reading did not capture it.
• Where visitors should go in an evacuation, and whether alerts and broadcasts are given in English.
• Whether 110 and 119 calls are answered in English. The pages we read did not say.

Related guides

• How do you get to Hakone from Tokyo? Trains, passes and the ropeway
• What are Lake Ashi and the old Hakone Checkpoint?

Sources

All URLs retrieved 2026-10-04.

1. 火山活動の状況（箱根山） (Japan Meteorological Agency) — (Level 1 on the day; forecast of 7 October 2019; current cautions)
2. 箱根山 (Japan Meteorological Agency) — (monitoring instruments)
3. 箱根山 有史以降の火山活動 (Japan Meteorological Agency) — (past eruptions, the 1953 landslide, 2015 and 2019)
4. 火山の状況に関する解説情報（箱根山第１号） (Japan Meteorological Agency) — (earthquakes under southern Lake Ashi, July 2025)
5. 箱根山の火山活動解説資料（令和８年８月） (Japan Meteorological Agency) — (August 2026 activity; steam height; next report date)
6. 箱根山の噴火警戒レベル (Japan Meteorological Agency) — (response at each level; specific areas; start and revision dates)
7. 箱根山の噴火警戒レベルについて (Hakone Town) — ("Hakoneyama" is a volcano name; levels since 2009; revised in 2025)
8. 箱根山火山ハザードマップ及び箱根山（大涌谷）火山避難計画の改定について (Hakone Town) — (2025 revision; specific areas changed; danger not increased)
9. 箱根・大涌谷情報 (Kanagawa Prefecture) — (health warning on gas; restricted zone; road hours; trail closure; nature trail fee)
10. 大涌谷橋の火山ガスについて (Hakone Town) — (gas monitoring at Owakudani Bridge; 2 ppm and 10 ppm steps)
11. 大涌谷引率入場 オンライン予約 (Hakone Town Tourist Association) — (nature trail booking, group size, times, fee, Japanese-only explanations)
12. 箱根ロープウェイ (Hakone Navi, Odakyu Hakone) — (gas and weather stoppages)
13. 駒ヶ岳～神山間におけるハイキングコースの開放について (Hakone Town) — (trail between Komagatake and Kamiyama reopened 28 March 2025)
14. 交通規制情報 (Hakone Town) — (rain thresholds for road closures; buses; Hakobo Map)
15. 入浴中における事故防止について (Hakone Town) — (bath accidents and why they happen)
16. Dial 110 to notify the police (Kanagawa Prefectural Police) — (where 110 calls go; what the call taker asks)
17. Guide for Ambulance Services (Fire and Disaster Management Agency) — (call 119 for an ambulance; anyone in Japan can use it)
18. 救急隊からの折り返し電話連絡（プレアライバルコール） (Hakone Town) — (ambulance crews may call back)