Oirase Gorge — Pristine Stream & Moss-Covered Forest

Oirase Gorge (奥入瀬渓流) runs 14 kilometers from Lake Towada's outlet through old-growth forest where moss coats every boulder and root. The stream flows crystal-clear over bedrock — you can count pebbles at 2-meter depths. Beech and maple trees arch overhead, filtering sunlight into green-tinted shade. Every 200–300 meters, a waterfall tumbles over volcanic rock shelves, adding white noise to birdsong.

Late October transforms the gorge into Tohoku's premier autumn color destination. Maples turn crimson and yellow while evergreen hemlocks stay dark green, creating three-color layers. Photographers arrive at dawn to shoot Kumoi Waterfall (雲井の滝), where water cascades through moss so thick it looks like green fur. Summer brings cool forest shade 5°C below valley temperatures, making the path a refuge from August heat.

The paved path follows the stream's entire length, flat enough for elderly visitors. Full walk from Nenokuchi to Yakeyama takes 4–5 hours. Most people hike the middle 8km (Ishigedo to Yakeyama, 2.5 hours), hitting the densest waterfall concentration.