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Kiyotsukyo Gorge Tunnel — Suspended Glass Platform Over Emerald River

Published: Jul 22, 2026

Updated: Jul 22, 2026

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Kiyotsukyo Gorge Tunnel — Suspended Glass Platform Over Emerald River

Kiyotsukyo Gorge is a 750-meter-long ravine carved by the Kiyotsu River through solid granite, with vertical cliffs rising 50–100 meters on both sides. The gorge was inaccessible until 1996 when a pedestrian tunnel was blasted through the cliff face, allowing visitors to walk inside the mountain while observing the gorge through periodic window openings. In 2018, the tunnel was redesigned by artist Ma Yansong, who installed a mirrored stainless-steel 'Periscope' observation chamber at the tunnel's end — a polished metal box suspended over the emerald river water, reflecting both gorge walls and sky to create an infinite-mirror effect.

The gorge water is an otherworldly turquoise color (mineral suspension from upstream granite erosion) year-round, but is most vivid October–November when low water flow and autumn sunlight intensify the blue-green hue.

Essential Information

Opening Hours

8:30–17:00

Closed: Closed January–March due to snow

Entrance Fee

¥1,000

Best Season

Late October–early November for turquoise water + crimson autumn foliage; visit 10:00–14:00 for best Periscope chamber lighting

Visit Duration

1–1.5 hours round-trip through tunnel including Periscope observation chamber

Getting There

Access Information

Koide, Tokamachi City. 25-min drive from Echigo-Yuzawa Station or 60-min local bus (infrequent service, check schedule). Tunnel admission: ¥1,000. Hours: 8:30–17:00 (closed January–March due to snow). Walking time: 30–40 min round-trip.

Insider Guide

Premium

**Periscope observation timing:** The reflective chamber is most photogenic 10:00–14:00 when sunlight penetrates the deep gorge and illuminates the chamber interior. Bring a lens cloth — the mirrored surfaces show fingerprints and water spots. The chamber can hold approximately 15 people; on weekends expect 10-min waits to enter. **Tunnel lighting:** The Ma Yansong redesign includes LED installations that shift color based on season — blue-white in winter, green in spring, gold in autumn. The effect is subtle during daytime but striking if you visit near closing time (16:30–17:00) when natural light fades and the LEDs become dominant. **Autumn color:** The gorge rim supports deciduous forest (mostly maple and beech) that turns crimson and orange late October to mid-November. The contrast of turquoise water, autumn foliage, and gray granite cliffs is the iconic Kiyotsukyo image. Peak color usually occurs November 1–7.

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