Dogashima Marine, Nishiizu

Dogashima Marine operates Japan's premier cave excursion boat tours along the dramatic coastline of western Izu Peninsula in Shizuoka Prefecture. Located in the Fuji-Hakone-Izu National Park, this scenic area is renowned for its unique ria coastline formed by volcanic activity and natural erosion over millennia. The company has been providing boat tours since the region's development as a tourist destination, offering visitors access to the area's most spectacular sea caves and rock formations.

The main attraction is Tensodo Cave, designated as a national natural monument in 1935. This remarkable sea cave features three entrances with the southern entrance stretching 147 meters in length, allowing boats to enter safely. The cave's defining feature is a large circular opening in its ceiling that creates a natural skylight, casting ethereal blue light onto the emerald waters below. The name "Tensodo" translates to "window to heaven," reflecting the mystical quality of sunlight filtering through this geological formation.

Dogashima Marine operates four different boat routes with high-speed cruisers that depart every 15-20 minutes during peak seasons. The standard cave excursion takes visitors through the intricate coastline to explore multiple caves and witness the famous "blue cave" phenomenon. Tours also showcase Sanshiro Island and other notable rock formations along the deeply indented coastline that characterizes this part of the Izu Peninsula. The boats are designed specifically for cave exploration, allowing safe passage through narrow entrances while providing optimal viewing of the dramatic geological features.

Adult tickets cost ¥1,500 while children's tickets are ¥700. The tours operate year-round though schedules may vary by season. Visitors can also enjoy dining at the marine station, which offers traditional Dogashima Gozen meals featuring local specialties including simmered red bream, sashimi, and tempura. A gift shop stocks regional products, marine-themed merchandise, and local sake.

Access to Dogashima Marine requires travel to Nishiizu town on the Izu Peninsula. The most convenient option is driving, as public transportation to this remote coastal area is limited. From Tokyo, visitors typically take the JR Tokaido Line to Atami, then transfer to the JR Ito Line to Shimoda, followed by local buses to Dogashima. The journey takes approximately 3-4 hours by public transport. Marine Station Dogashima serves as the departure point for all boat tours and houses ticket sales, dining facilities, and visitor information services.