Travel Reference
In-Depth Information
to know what it was), there doesn't seem to be much real housing on the island. However,
there is a public campground.
In any case, regardless of whether anyone actually lives on Ōjima, most visitors don't
come here to stay. They come to visit the Tatami-ishi pentagon- and hexagon-shaped stones
that look like giant tortoise shells. These strange rocks are on the south coast of Ōjima and
spread along the beach for about 575 feet (175 meters) and offshore for about 80 (25 meters).
Altogether, there are some 1,000 of them. Obviously, more of them be seen at the lowest tides.
The stones are a protected natural treasure of Okinawa Prefecture. Although that probably
means that no one is allowed to dig them up, or remove or damage them in any way, visitors
are allowed to walk on them and take photographs. There's no charge.
Because of their resemblance to either the interlocking sections that make up a turtle's
carapace or a room full of traditional Japanese floor mats, they are called both “turtleshell
rocks” and “tatami-stones.” Although by no means common, this unusual natural phe-
nomenon is seen in several places around the world. It is caused when andesite- or basalt-
type lava, extruded from a volcanic eruption, gradually cools to rock and splinters or crystal-
lizes along what are called columnar joints. Such formations are rare. The erosion of millions
of years by ocean waves has worn down the rocks to nearly flat. Now they look as if someone
has manufactured them, but of course they are natural works of art.
The beach on which the rocks are found extends east for more than three-quarters of
a mile (1 kilometer), the entire southern shore of the island. On shore, immediately above
the rocks is the relatively new Kumejima Sea Turtle Museum (
久米島ウミガメ館
; Kumé-jima
Umi gamé-kan). It opened on Ōjima a few years ago and has exhibits and displays on the life
cycle of these intriguing creatures. The museum has been successful in breeding several en-
dangered species of sea turtles.
Tatami Mat Stones
