Mount Tarumae Summit / Outer Rim Trail was added to Your Favorites!
Shikotsu-Tōya NP., Hokkaido
Claim this place to tell your story your way.
Cloud hid Tarumae’s summit as its famous lava dome grew: it appeared between 17 and 19 April 1909, reaching about 120 m high and 450 m wide. Hokkaido designated it a natural monument in 1967.
The outer rim encloses a crater about 1.2 × 1.5 km wide, shaped by the 1739 eruption. Ash was so thick that historical accounts say daylight turned dark for 2–3 days—a dramatic origin for today’s hiking skyline.
Tarumae comes from the Ainu river-name Taoromai, “something on a high riverbank”—a clue to the nearby Tarumae River. The mountain was also called Ofui-nupuri, “burning mountain,” for its volcanic character.
A pink alpine flower here is an outsider: komakusa was planted on Tarumae in 1986. At one removal site, its numbers fell from about 3,000 plants in 2024 to 1,000 in 2026, helping native Iwabukuro recover.
On the trail northwest of the dome toward Fuppushidake, some rocks wear cracked, loaf-like skins. These “breadcrust bombs” are once-molten lava fragments whose outsides cooled while gas kept expanding inside, splitting the crust.
At just 1,041 m, Tarumae has about 90 plant species recorded from the 7th station to the summit, including native Iwabukuro—Tarmaisō, or “Tarumae flower”—and other alpine blooms.
Tarumae’s present dome had a predecessor: formed in 1867, it was shattered by the 1874 eruption, which hurled rocks over the outer rim onto the mountainside. The dome visible today is the next chapter, born in 1909.
In June 2023, a park ranger spotted a skylark carrying a plant root or twig near Tarumae’s summit, apparently nest material. With vegetation sparse up there, even a tiny bundle for building is hard-won.
