Mt. Aso (阿蘇山)

On October 20, 2021 Mt Aso has once again erupted, so the mountain is currently off limits. Please avoid climbing it until the volcanic alert level is lowered. 

Last updated: September 21, 2020

Mt. Aso is an active volcano located about an hour outside of Kumamoto city in central Kyūshū. The peak is popular with hikers on the rare occasion that the mountain is actually open. Recent eruptions of the Nakadake crater have forced the closure of the hiking trails, but as of September 2020 the main trails have now reopened.

The hike: At Suisenkyo parking lot, you’ll find the abandoned ropeway station, a small visitor’s center and a restroom. You might be tempted to take the trail just to the left of the restrooms but that is the descent trail. Instead, head over to the other side of the parking lot (perpendicular to that trail) to find the Sensuikyo-one route (仙酔峡尾根ルート登山口). The trailhead is marked by a small wooden bridge spanning a ravine, so cross over the bridge and follow the remnants of the old concrete path up towards the spur. After passing by a rest bench, look for the kanji for Takadake (高岳) hand-painted on a rock and follow the trail through a short area of bush to reach the start of the long ridge. The volcanic rock looks as if it’s been cemented to the mountainside but in fact it’s a natural process that allows for good traction for your hiking shoes. The route is well-marked and easy to follow: just look for the generous amount of yellow arrows and circles painted on the rocks. As you climb higher, be sure to look back for the excellent views of the Kujū mountain range rising up across the valley. It will take anywhere from 90 minutes to 2 hours to reach the summit plateau, so take your time and enjoy the excellent scenery. There’s also a fair bit of scrambling in the initial part of the climb, but as the spur steepens you’ll reach an exposed area with a fixed rope. Take care with your footing here. Above this section is a series of switchbacks until you pop out onto the ridge just to the left of the high point of Takadake. In clear weather you can see that you’re standing on the edge of an ancient volcanic crater covered with lush greenery. There used to be a trail that completely circumnavigated this crater but it’s since fallen into disuse and is incredibly overgrown. Look down into the crater and you will see a small stone shelter (called Tsukimi hut). Some hikers head left here on the ridge for the east peak called Takadake Tōhō (高岳東峰). The route to the summit has fallen into disrepair and it’s not recommended unless you want a close-up view of the spires of Mt Neko. Instead, turn right on the crater rim for the short 10-minute climb to the summit of Takadake, the highest point in the Aso mountain range. This is a great place to enjoy lunch before continuing along the ridge. Drop west towards the active crater down a well-used trail for Nakadake. Watch your footing on the loose rocks as you drop for 5 minutes to a junction. Ignore the trail left to Tsukimi shelter and stay on the main ridge. The gradient eases and it’s a fun ridge walk for 15 minutes to the summit of Nakadake (中岳). Just before the summit you will reach a junction. If you came by bus then you probably climbed up here from the touristy side of the mountain. This trail leading left from here follows the crater rim before dropping steeply down into the crater floor and the martian landscape of Sunasenri-ga-hama (砂千里ヶ浜). From there it’s an easy walk out to the bus stop (but watch out for toxic gases blowing over from the active crater). However, ignore this path and head straight to the summit of Nakadake. Continue on the ridge past the summit, taking care to watch your footing on the slope just below the summit, as loose rock makes for poor traction. The terrain abruptly changes, as you traverse through ash deposited in the 2014 eruption. Signposts warn of volcanic gas and you won’t believe your eyes as the trail heads towards the active crater, an area called Kakōhigashi Observatory (火口東展望所). You’ll soon traverse directly below a crumbly headwall on your left – take care of falling rocks on the narrow traverse. Stay on the ridge, following the yellow paint marks in times of poor visibility. The trail drops to a small saddle before climbing up to the remnants of the observatory, which affords spectacular views of the active crater. Just before the top of the viewpoint, a trail heads right towards the ruins of the concrete ropeway building. Ignore this and head to the observatory before retracing your steps to this junction and descending on the east trail past the emergency bunkers to the top of the old ropeway. DO NOT attempt to enter the ruins, as the building is incredibly unstable and was heavily damaged in the eruption. Instead, take the path to the right of the structure along the crumbly asphalt of the disused trail. Despite the poor condition of the trail, it’s an easy descent that will lead you back to the parking lot in about 40 minutes.

When to go: This hike can be done year round, but be prepared for snow during January and February. Click here to see the wonderful snow scenery. The peak is frequently closed due to volcanic activity, so please check here for the latest information (in Japanese).

Access: From Kumamoto (熊本) station, take a train on the JR Hohi Line (包皮線) to Miyaji (宮地) station. From there, either take a taxi (costing around 1500 yen) to Sensuikyo (仙酔峡) or try your luck hitchhiking. If you just want to see the active caldera or approach the peak via Sunasenri-ga-hama, then you can take a bus in front of Aso station (阿蘇駅前) to Asosan Nishi Eki (阿蘇山西駅). The bus takes about 35 minutes and there are 4 buses daily (no booking required). Click here for the schedule.

Live web cam: Click here

Level of difficulty: 3.5 out of 5 (elevation change 692m)

Total Round-trip Distance: 7km (4 to 6 hours)

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One Comment on “Mt. Aso (阿蘇山)”

  1. Morten Sylvest Olsen Says:

    Update from 10th of November 2015: Probably not surprising, due to the recent eruption at Naka-daka, all of the trails in that area are currently closed. Access to the lower visitor centre area, and a short touristy walk onto the large grassy area with views up towards Naka-daka was possible. Photos in the lower visitor centre shows the eruption cloud covering parts of the parking lot, pretty impressive stuff, glad one wasn’t hiking there on that particular day.

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