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Shiretoko NP, Hokkaido
Claim this place to tell your story your way.
In a 2019 survey, Oronko Rock had 211 black-tailed gull nests—the largest count among the colonies surveyed on Shiretoko’s Utoro side. The cliffs are busy family territory in summer.
In 2019, great cormorant nests on Oronko Rock jumped from 9 to 77 in a year—about one-third of all nests counted across the Shiretoko Peninsula. Researchers suggested the rock may offer refuge from predators.
Oronko Rock and nearby Triangle Rock are thought to have once been one mass of rock. Waves and drift ice gradually wore away the middle, leaving the separate shapes visitors see today.
Oronko’s flat top is about 58 meters above sea level, close to the height of nearby Utoro’s plateau. The heritage trail explains that this level began as a wave-cut sea platform about 120,000 years ago, later raised by uplift.
Excavations on Oronko Rock found shallow hearths in layers from different periods, suggesting people used the summit repeatedly. No pottery or stone tools were found, so the hearths could not be dated precisely.
Deer cannot easily reach the summit, so plants there escape some grazing. The Environment Ministry notes that Ezo-yomogi-giku is known from only a few places in Japan, including Oronko Rock, Rishiri Island, and Rebun Island.
A university heritage guide records older Ainu names for the rock: Samakke-watara, “lying rock,” and Orokushuma, “rock sitting there.” It says Oronko may have developed from Orokushuma; the local tourism association also gives a different explanation, linking the name to the Oronko people.
A local legend—not verified history—tells how Ainu attackers made a fake stranded whale from seaweed and sand, then laid out fish. The rock’s defenders supposedly came down to claim it and were ambushed.
