🗺️ Iozumi Suichu Chōnyūdō (Iozumi Water Cave)

The Inazumi Underwater Limestone Cave was formed 300 million years ago during the Paleozoic era. It was submerged 300,000 years ago due to the eruption of Mount Aso, creating a rare underwater stalactite cave. With a total length of about 1 kilometer, it is the longest underwater stalactite cave in Japan, and exploration activities are still ongoing. The cave is divided into two parts: the new cave and the underwater cave. The rocks on the ceiling have been eroded into bell-shaped formations known as "bell caves," while the "Dragon Palace" is illuminated in a dreamlike blue light, and the "Manifestation Waterfall" features clearly visible rock textures submerged underwater. The natural artistry shaped by time is incredibly rich. The temperature inside the cave remains at a comfortable 16 degrees Celsius year-round, providing a naturally pleasant space that is warm in winter and cool in summer. Visitors can also rent a full set of equipment to enjoy snorkeling and scuba diving in the underwater stalactite cave (fees apply and advance reservations are required). The Inazumi Underwater Limestone Cave area is quite large, and while visiting the stalactite cave, you can also explore many attractions, such as the "Inazumi Shoryu Great Kannon," the highest in Oita Prefecture, and the "Showa Time Travel Romance Seat," which recreates the atmosphere of the Showa era.

A rare underwater stalactite cave that is hard to find in today's world. In addition to the stalactites, there are many rich facilities available. The temperature inside the cave remains at a constant 16 degrees year-round. You can also experience diving here. The cave floor is very slippery, so it is recommended to wear shoes with good grip when visiting.