UNESCO Geoparkジオパーク

The Fossa Magna Museum is genuinely excellent by any global standard. Six permanent exhibition zones cover Itoigawa’s world-famous jade (raw specimens pulled from nearby gorges), the geology of the Fossa Magna, fossils including the unusual Nipponites ammonite, and an immersive floor-and-wall projection of how the Japanese archipelago formed.

Critically, all signage is in English and Japanese. The museum offers a free mineral identification service, bring stones from the Jade Coast and staff will tell you whether it’s genuine jadeite, nephrite, or an ordinary rock.

Below the limestone walls of Mount Myōjō, the clear blue-green waters of the Kotaki River flow between boulders that are not boulders, they’re massive chunks of raw jadeite. This is thought to be the first jade production site in Japan, and possibly the world. The Jōmon people were mining here over 7,000 years ago.

Today it’s a National Natural Monument, so you cannot remove stones, but you can wade into the shallows and touch the unmistakable milky green of jade in running water. A 0.5–1 km loop trail passes the largest visible jadeite boulders.

Sitting on a plateau 540 m above sea level at the base of Mount Myōjō (1,188 m), Takanami-no-Ike is a serene alpine lake that reflects the mountain in glassy stillness. Mount Myōjō itself was once a coral reef on the ocean floor 300 million years ago, its rock walls still contain marine fossils.

In autumn the surrounding forest turns brilliant gold and red; in winter the pond sometimes freezes. Walking trails, picnic spots, and a small campground surround the lake.

The quietest stop delivers the most remarkable payoff: an exposed section of the Itoigawa–Shizuoka Tectonic Line. A modest set of stairs brings you face-to-face with two rock faces from different geological eras pressed against each other. One side is ~400 million years old. The other is ~16 million years old. The line between them is the seam where eastern and western Japan meet.

There’s also a small section of pillow lava, the distinctive rounded rock formed when lava cools underwater. The park sits on the grounds of Watanabe Shuzōten sake brewery, making it easy to combine with a tasting.