Yoshioka-Kaitei Station (吉岡海底駅 Yoshioka-Kaitei-eki) is a train station within the Seikan Tunnel on the Kaikyo Line in Fukushima, Hokkaidō, Japan. It is operated by Hokkaido Railway Company. The station is located 149.5 metres (490.5 feet) [1] below sea level, making it the deepest underground station in the world.