初島

Shotojima is an artificial island standing in the Ariake Sea roughly 2 kilometers off the Omuta coast. The circular structure measures about 120 meters in diameter and was built on soft seabed using wire mesh and stone foundations to ensure stability.

The island was built between 1949 and 1951 as a ventilation hub for the Mitsui Miike coal mine tunnels running beneath the Ariake Sea. It served as a critical support structure for the mining operations that extended far offshore.

The island represents the industrial heritage of coal mining in Japan, demonstrating the engineering methods used to maintain worker safety in underground mines.

The island is visible from shore but generally not open for direct visits since it remains a historic industrial site. Views from the mainland coast or approaching waters offer the best perspective of the structure.

Large mechanical fans extracted contaminated air from the mine shafts below and released it to the atmosphere. This system was groundbreaking for protecting workers who labored hundreds of meters beneath the seafloor.