Northwest Gunma · Asama HighlandsNo.1107★★Open in map →

Onioshidashien Lava Park

natureOff the trail — and worth it

A park laid out on the black lava that poured off Mount Asama and set where it stopped. Paved paths thread between the broken rocks, past a Buddhist hall, and on to a trail with a long view over the highlands.

FromKaruizawa Station
~40 minSeibu bus from Karuizawa
Get off atOnioshidashien (Seibu Kanko Bus)
From there
Onioshidashien Lava Park

Directions ↗

The sweet spot

This is a paid, well-signposted sightseeing park on a main highway route, so it is not a hidden find. What thins out is distance from the gate: most visitors circle the entrance, the restaurant and the hall, which leaves the inner sanctuary path and the upper plant trail comparatively calm.

Where it is

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What to look for — in walking order

The lava walkwaySpringField1967 / CC BY-SA 3.0

The observation restaurantthe building just inside the gate, with the rock field below its windows
The lava walkwaypaved paths threading between blocks of black rock, level enough for an unhurried circuit
Asamayama Kannon Hallthe hall at the centre of the park, where a Sho-Kannon image is enshrined as a guardian against misfortune
The inner sanctuary patha quieter branch running past the hall to the Homura Kannon image
The alpine plant trailthe upper route, with alpine flowers in the rock from May and long views over Tsumagoi

How to actually get there

Karuizawa Station to Onioshidashien (Seibu Kanko bus, about 40 minutes).
Through the ticket gate and onto the paved lava walkway, passing the restaurant building.
Follow the path to the Kannon hall at the centre, then take the inner sanctuary branch and the upper plant trail before turning back.

Seibu Kanko bus from Karuizawa Station: Karuizawa Station to Onioshidashien by Seibu Kanko bus, about 40 minutes on the Kusatsu and Manza route. The bus climbs the Onioshi Highway and sets down at the park gate. Services are timetabled rather than frequent, so check the departure before you set out.
Return from the gate stop: Buses back to Karuizawa leave from the same stop at the gate. This is a mountain route and the evening timetable thins out, so note the last departure when you arrive rather than at the end of the day. Karuizawa puts you back on the Hokuriku Shinkansen for Tokyo or Nagano.

Directions from my location (Google Maps) ↗

About the place

The ground here is the lava itself. It came down the north flank of the volcano, cooled into jagged grey-black blocks, and was never cleared away — the park simply laid walkways over and between them. Pines and low alpine shrubs have rooted in the cracks, so the place reads as rock first and garden second. The paths branch as you go: a main circuit near the gate, a quieter inner route out to a small hall, and an upper trail that leaves the rock behind for open highland views. Gunma's tourism material has long billed the landscape as one of the world's three great rock curiosities.

How to enjoy it

The gate opens at 8:00, and an early bus up from Karuizawa puts you on the rock before the coach groups arrive. On the 18th of each month the hall's doors are opened. Give the visit more time than the main circuit suggests, because the inner path and the upper trail are where the walk turns into something more than a roadside stop.

Background & history

Mount Asama erupted through the summer of 1783, in the Tenmei era, and the disaster reshaped the villages below. Lava spilled down the northern slope and hardened into the field the park now occupies. Villagers who saw it said demons had shoved the rocks out of the crater, and the name Onioshidashi kept that image. In May 1958 a hall was raised at the centre of the site, a branch of Kan'ei-ji in Tokyo, to console those the eruption killed.

Before you go

Cash: Admission was listed at 700 yen for adults and 500 yen for elementary-school children when checked on the park's official site. The bus operator also sells an unlimited-ride ticket for the Karuizawa to Onioshidashien route, bought from the driver on board rather than at a counter.
Good to know: The operator notes that opening periods and hours change with the season and that the park may suspend operation, so confirm before a winter trip. The lava field is open ground at altitude with little shade or shelter, wind and fast-moving cloud are normal, and the surface is uneven underfoot.
Another way: Buses also run from Naka-Karuizawa Station, about 30 minutes, and from Manza-Kazawaguchi Station on the JR Agatsuma Line, about 25 minutes. By car it is roughly 30 km from the Usui-Karuizawa interchange via Naka-Karuizawa and the Onioshi Highway.
After you get off: The bus sets down at the park's own stop beside the car park and ticket gate. The walkways start immediately past the gate, and you are among the rocks within a couple of minutes.