Gujo · JP

Miyama Limestone Cave

Deep in the forested hills around Gujo-Hachiman in Gifu Prefecture, Miyama Limestone Cave (美山鍾乳洞) is one of Japan's largest three-dimensional maze caves. Unlike most show caves that run along a single horizontal tunnel, this one was carved as groundwater slowly dissolved Permian limestone from the top down, stacking chamber upon chamber over some 250 million years. The result is a vertical labyrinth spread across several levels with roughly 70 metres of height difference, connected by stairways that drop and climb through passages of softly curved walls and dense stalactites. Designated a Natural Monument by Gujo City, the cave was deliberately left unaltered when it opened to visitors in 1969, so what you walk through is the raw, natural formation rather than a landscaped grotto. Inside, the air holds a steady 13–14°C all year, which makes the cave a genuine natural refrigerator on a hot summer afternoon and a pleasantly mild hideout the rest of the season. The lit tourist route runs about 800 metres of a total length of more than 2,000 metres and takes roughly 30–40 minutes at your own pace; beyond it, an unlit section of the system hosts guided caving tours for the more adventurous. The cave is also famously unusual for two things: it welcomes visitors' leashed pets underground, and its facility offers a hands-on food-sample making class, a nod to Gujo-Hachiman's status as Japan's food-sample capital.