Information about Ōkubo-no-Kazaana (大久保の風穴)

 In Mountain information

Suite à ma première sortie spéléo de 2013 dans la grotte d’Ōkubo-no-Kazaana (大久保の風穴), voici les informations sur l’accès et la sécurité si vous voulez allez découvrir la grotte.

Informations générales

Ōkubo-no-Kazaana est une grotte situé le massif d’Abukumakōchi (阿武隈高地) dans la préfecture d’Ibaragi (茨城県). C’est une grotte connue qui était autrefois une “grotte touristique” qui est même indiquée sur la carte Google. Constituée de plusieurs puits, dont le plus profond fait une quinzaine de mètres, c’est une grotte parfaite pour l’entraînement aux manips de cordes en spéléo.

You will find on this page a partial topo (vertical view), showing the bottom part of the cave.

Outings examples

Ōkubo-no-Kazaana (大久保の風穴) video

This is a video of the caving SRT training I did with my club last May in Ōkubo-no-Kazaana (大久保の風穴) while exploring the cave

SRT training at Ōkubo-no-Kazaana (大久保の風穴)

After starting back climbing last week-end, yesterday I was back caving. We had plnned to go back to Rōkokudō (瀧谷洞) but due to heavy rain weather forecast we changed our plan and went to [...]

Access from Tōkyō

To check train schedules, use the following site (in English) :

Even if it is more convenient to go there by car with all the gears and change necessary, it is possible to go to the cave by public transportation. From Tōkyō, there are direct trains from Ueno (上野) station on the JR Jōbansen line (常磐線) to Hitachitaga (常陸多賀) station. It takes bout 1:40 and costs 1780¥. From there take a bus to Nakamaru-danchi (中丸団地) and get off at Nakamaru-danchi-nyūguchi (中丸団地入口) (timetable: Then follow the river towards the forest and the the forest trail for less than 1 km up to the cave, located few meters aboves a big sign warning not to make fire.


The cave’s entrance is about a 100 meters away from the forest road so there’s no need of any map..


GPX file GPS: ookubo-no-kazaana.gpx.


Caving is an almost unknown activity in Japan. Don’t expect anything from rescue teams which are absolutely not prepared nor trained for interventions in such a specific environment. You are totally on your own. In addition to this, there are very very Japanese insurance covering this activity (classical outdoor or mountaineering insurance do not cover the activity, to the best my knowledge only jRO insurance covers it.). That said you should better not put yourself in a difficult situation and always choose the safest choice. If you are not sure, give up. Here precaution prevails.

The cave has several shafts which requires to use ropes and caving gears and techniques. One 50 meters rope as well as two 30 meters ropes will be the minimum if you want to explore all the cave. The cave is equipped with expansion bolt anchors (some a bit old) to go down or traverse the shafts but you will have to bring your own bolt hanger (8mm pad) as well as your own maillons. Except if I’m wrong, about 15 will be enough.

Okubo-no-kazaana - bolt holesOkubo-no-kazaana - bring your own bolts

The cave is inhabited by bats. Normally Japan bats do not carry rabies (confirm with Japan Infectious Disease Surveillance Center IDSC, 国立感染症研究所 感染症情報センター) but their feces can be a vector of infectious disease. It is mandatory to wear gloves (I recommend to have surgical latex cloves under your regular gloves) and to avoid rubbing your eyes or your mouth with your hands.

Okubo-no-kazaana - bat familyOkubo-no-kazaana - lonely bat

Finally, avoid caving when heavy rain because of the risk of flooding in the galleries.

Check the weather forecast on the English page of the Japan Meteorological Agency :

Other useful numbers in case of emergency

  • Hitachi (日立警察署) town police station at 0294-22-0110
  • Ibaragi prefecture police headquarter (茨城県警察本部) at 029-301-0110.
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