Inazumi Underwater Cave

OITA NATURE

The Inazumi Underwater Cave was formed 300 million years ago during the Paleozoic era. It took its current form 300,000 years ago when it was submerged by a great eruption of Mount Aso. There is lots to see inside this underwater limestone cave, unusual worldwide, including underwater stalactites, corallite, the “Bell Hall,” where bell-shaped sculptures were formed on the ceiling, and helictites.
There are countless stalactites, deep pools with a depth of over 40 meters, and clear streams that gush from unknown recesses of the cave. The contrast of the beautiful, ever-changing stalactites takes visitors into a world of illusions. The temperature inside the caves is 16 degrees all year round - cool in the summer and warm in the winter, making this underwater limestone cave wonderful to see all year round.