Tatami-ishi (Tatami Rocks) – Kumejima-chō, Japan - Atlas Obscura
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Kumejima-chō, Japan

Tatami-ishi (Tatami Rocks)

Unusual hexagonal rocks formed by cooling lava named for their resemblance to traditional Japanese tatami mats. 

Tatami-ishi 畳石 (Tatami-Rocks) is a Nationally Designated Natural Monument located on the south coast of Oujima 奥武島 (Ou Island).

These pentagonal and hexagonal shaped rocks, formed by andesite magma cooled under a geological process called columnar jointing, are called Tatami-Rocks because of the resemblance to the tatami mats of traditional Japanese home design.

Water erosion has leveled and smoothed the tops of the rock structures.

Know Before You Go

Check daily tide charts, best viewed at low tide.

A bridge connects Oujima to Kumejima.