Dogashima, located in Nishiizu Town, Shizuoka Prefecture, is a scenic spot with a unique ria coastline, various large and small strange rocks, and scattered islands. One of the most popular activities is a tour of the caves on a sightseeing boat. Among the many sea caves created by wave erosion, the national natural monument "Tenmado Cave" is called the "Blue Cave" because the sunlight pours in through a gaping hole in the ceiling and the sea surface shines emerald green, and it attracts visitors with its mysterious beauty.

If you go inside the cave on a sightseeing boat, you will be taken aback by the color of the water that changes from moment to moment depending on the amount of light that penetrates. On the approximately 20-minute cruise, in addition to Tenmado Cave, you can also slip between steep rocks and see the strange rocks created by nature up close, making it a dynamic experience. The view of Dogashima from the boat will leave you with a different impression than from the land. On days when the waves are calm, you can enter the cave and experience an even more fantastical view up close.

Dogashima is located on the west coast of the Izu Peninsula and is also known as a great spot for watching the sunset. After touring the caves, we recommend enjoying fresh local seafood while watching the beautiful sunset. A tour of the caves in Dogashima, where you can feel the mystery and grandeur of nature, is sure to be a highlight of your Izu trip.

[Trivia]
Tenmado Cave is called "Tenmado" because the ceiling inside the cave is round and missing. The light that shines through this hole illuminates the sea surface, creating a fantastic "blue cave." The cave is made of tuff, a relatively soft rock, and was formed over a long period of time by erosion by the waves.

[Hidden Spot Information]
In addition to taking a sightseeing boat, you can also walk along the promenade in Dogashima Park and look down on Tenmado Cave. From the promenade, you can see the sightseeing boats coming and going inside the cave, and you can understand the structure of Tensodo Cave from a different angle. Also, at low tide, you can see the "tombolo phenomenon" where the mainland and Sanshiro Island become connected, and you can walk across to the island.