Tomogashima has five old cannon bases and one fortress. Cannon base is against enemy battleship attacks. On the other hand fortress is used to fight against the enemies who landed. Tiger Island fort equipped with 9 cm fire cannon. Currently many of the fire cannons are covered with ground and trees, but you can see the remnants of brick-made underground formula covering part (pencil) ammunition branch. The embankment that crosses Tōdo is flooded in the middle and is extremely dangerous except at low tide. As we may not be able to pass at the time of high tide, we recommend examining the tide level on the day and the time of low tide. It takes about 1 hour from Nonaura pier, prepare stuff such as shoes and have enough time.