Oirase Mountain Stream Gorge (Special Scenic Beauty & Natural Monument)

Category: Primeval Stream Gorge & Moss Forest Trail | Location: Okuse, Towada City, Aomori Prefecture

Flowing 14 kilometers from Nenokuchi on Lake Towada down to Yakeyama in Aomori Prefecture, the Oirase Mountain Stream (Oirase Keiryu) is one of Japan's most celebrated alpine river valleys, doubly designated as both a Special Place of Scenic Beauty and a Special Natural Monument. Embraced by primeval subarctic virgin forests of Siebold's beech, katsura, and Japanese maples, the rocky canyon floor forms a microclimatic wonderland sheltering over 300 species of velvet-green mosses and delicate lichens blanketing ancient volcanic boulders and fallen timbers, evoking a magical fairy-tale atmosphere. A gently graded, beautifully maintained hiking trail meanders directly along the riverbank, inviting travelers to stroll alongside the crystalline currents at an intimate proximity. The visual drama peaks at the iconic Ashura no Nagare rapids, where torrential waters surge vigorously around moss-draped boulders under a verdant leafy canopy, sending up refreshing mists. Across the flat walking path, nature enthusiasts encounter fourteen distinct waterfalls, including the two-tiered 25-meter Kumoi-no-Taki Falls and the graceful, gossamer threads of Shiraito-no-Taki Falls cascading over fern-encrusted cliffs. Near the upstream entrance where the river departs the lake stands Choshi Otaki Falls—a monumental 7-meter-tall and 20-meter-wide horseshoe waterfall, the sole cataract directly straddling the main river stem. Its thunderous cascade historically acted as an impassable barrier preventing fish from swimming into Lake Towada, earning it the historic moniker Uodome-no-Taki ('Fish-Stopping Falls'). In late October, the forest canopy blazes in brilliant shades of gold, amber, and crimson to form an ethereal autumn tunnel over emerald moss, while deep winter transforms the waterfalls into towering pillars of turquoise frozen ice.