The Tombolo of Dogashima is a rare natural phenomenon that appears only at low tide. As the sea gently recedes, a sandy land bridge emerges, connecting the mainland to Sanshirojima Island. Located about 200 meters offshore, this group of four small islands becomes accessible on foot from spring through early autumn. During these seasonal low tides, visitors can experience the unique sensation of walking across the sea to reach the islands.

It is a rare phenomenon in Japan- usually islands are surrounded by the sea, but at low tide, the water retreats, revealing a bridge that was hidden beneath the waters. This only appears in a limited number of terrains and it is said that this phenomenon only occurs in less than 10 places throughout Japan.