A Mysterious Sight Straight Out of a Fantasy World

Designated as a National Natural Monument, this stunning location offers a surreal and mysterious landscape. After passing through a seaside cave from the Kokufu Beach, visitors emerge onto a vast, flat rock expanse known as "Senjōjiki", stretching out before them like a natural stone plaza the size of the Tokyo Dome. Scattered across the surface are round, stool-like rocks, creating a whimsical scene that looks as if it were pulled straight from a fantasy world, with the sea as its backdrop. The surface of the rock is crisscrossed with regular, grid-like cracks, resembling tatami mats—hence the name Tatamigaura.
This is a marine terrace, formed from seafloor strata deposited around 16 million years ago, which was uplifted by tectonic activity, including the Hamada Earthquake of 1872 (Meiji 5). Fossils of whale bones, shells, and other marine life can be easily spotted embedded in the rocks. The unique round "stool-like" formations are called nodules, formed when fossilized material acts as a nucleus for mineral buildup over time. With its wealth of unusual geological features, Tatamigaura is truly a “natural geological museum”—a place where science and fantasy beautifully intersect.

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