About
View of the natural skylight from inside Tensodo Cave, showing the dramatic beam of light penetrating the circular opening. Source: Wikimedia Commons
Dogashima (堂ヶ島) is a dramatic coastal area on the western shore of the Izu Peninsula, renowned for its striking volcanic rock formations and sea-carved caves. The crown jewel is Tensodo Cave (天窓洞, "Skylight Cave"), a natural monument featuring a spectacular circular opening in its ceiling through which sunlight creates an ethereal blue glow in the crystal-clear waters below. 🔗
Tensodo Cave is a 147-meter long sea cave carved by relentless wave erosion into volcanic tuff. Its most remarkable feature—the "tensō" (天窓, literally "skylight")—is a circular hole over 10 meters wide in the cave's ceiling, created when the weakened roof collapsed from erosion. This natural skylight is what gives the cave its name and creates the famous "blue grotto" effect that draws visitors from across Japan. 🔗
Geological Formation & Cultural Heritage
Dogashima's dramatic coastline was shaped by the Izu Peninsula's volcanic past. The peninsula was once an underwater volcano, and through successive volcanic eruptions, rock and volcanic ash accumulated and rose above sea level. The striking white tuff cliffs visible today are composed of volcanic ash that was compacted over millennia. 🔗
In 1935, Tensodo Cave was designated as a Natural Monument of Japan, a formal recognition of its importance to the nation's natural heritage. The surrounding Dogashima coast also carries the designation of "Place of Scenic Beauty," reflecting the Japanese aesthetic tradition of celebrating landscapes of exceptional beauty. The area is often called the "Matsushima of Izu," comparing it to one of Japan's Three Great Views. 🔗
The Izu Peninsula received UNESCO Global Geopark status in recognition of its significant volcanic and geological history, with Dogashima serving as one of the premier geosites showcasing the peninsula's underwater volcanic origins. 🔗
Visiting Information
Access:
- By Car (Recommended): Primary access method as public transportation is limited in western Izu
- From Tokyo: Approximately 3-3.5 hours via Tomei Expressway and Route 136
- Free parking available at Dogashima Marine and additional lots nearby
- Address for GPS: 2060 Nishina, Nishi-izu-cho, Kamo-gun, Shizuoka 410-3514
- By Public Transportation:
- From Shuzenji Station: 90 minutes by bus, ¥2,480 one-way, 1 bus per hour 🔗
- From Izukyu-Shimoda Station: 1 hour by bus, ¥1,680 one-way, 1-2 buses per hour
- Note: Limited frequency makes car rental highly recommended
Boat Departure Point:
- Dogashima Marine Station: 2060 Nishina, Nishi-izu-cho
- Contact: +81-558-52-0013
- Walking distance from parking areas (2-3 minutes)
Operating Hours:
- Boat tours: 8:15 AM - 4:30 PM (boats depart every 10-20 minutes) 🔗
- November hours: 9:00 AM - 6:00 PM (October-February schedule)
- Inquiry office: 10:00 AM - 4:00 PM
Admission Fees:
- Cave Excursion Tour (20 minutes):
- Adults: ¥1,300 (groups: ¥1,170)
- Children: ¥650 (groups: ¥580)
- Pre-school children: Free 🔗
- Alternative Tour Options:
- Dogashima Cruise (25 min): Adults ¥1,800, Children ¥900
- Senganmon Cruise (50 min): Adults ¥2,400, Children ¥1,200
- Geo-site Cruise (50 min): Adults ¥1,900, Children ¥1,100 (Saturdays only at 12:00 PM)
Facilities:
- Free parking at multiple locations
- Restrooms at Marine Station and parking areas
- Multi-language support (Japanese, Chinese, English)
The Experience
The Boat Tour
The Dogashima Cave Excursion is the definitive way to experience Tensodo Cave and the surrounding coastline. Departing from Dogashima Marine Station, the open-air pleasure boats navigate around the picturesque Sanshiro Islands and dramatic white tuff cliffs before entering the cave. 🔗
The boat enters through one of three sea-level entrances, and the atmosphere shifts as you enter the cave's cool interior. The vessel slows and pauses directly beneath the massive skylight for several minutes, allowing passengers to witness the famous beam of light. Sunlight streaming through the circular opening strikes the shallow, crystal-clear water, illuminating it in brilliant shades of emerald and cobalt blue. The effect is often compared to Italy's Blue Grotto, but is unique in that the light enters from above rather than through an underwater entrance. 🔗
Japanese-speaking guides point out key features throughout the journey. The tour also provides excellent views of Sanshiro Island, a collection of rocks connected to the mainland by a sandbar during low tide—a natural phenomenon called "tombolo." 🔗
Cliff-Top Walking Trail (Free Access)
From the free parking lot at Dogashima Park, a scenic promenade leads along the cliff top for about 5 minutes to an overlook directly above Tensodo Cave. The "Dogashima Promenade" offers a completely different perspective, allowing visitors to peer down through the skylight and see boats passing below. This vantage point provides excellent photo opportunities and a sense of the cave's scale. 🔗
The Nishiizu footpath (Dogashima course) is an easy 20-minute walk featuring cobblestones and stairs, offering superb coastal views throughout. While you cannot enter the cave from above, the cliff-top perspective is a worthwhile complement to the boat tour and requires no admission fee. 🔗
Sanshiro Island Tombolo
During low tide, a natural land bridge (tombolo) emerges between the mainland and Sanshiro Island, allowing visitors to walk across and explore the rock formations up close. This rare geological phenomenon adds another dimension to the Dogashima experience. Check tide schedules for optimal viewing times. 🔗
Practical Visiting Tips
November 8-9 Seasonal Considerations:
- Weather & Sea Conditions: Average daytime temperatures 16-17°C (61-63°F), nighttime lows 11-13°C (52-55°F). Sea conditions generally calmer than typhoon-prone late summer, though cancellations remain possible. Pack layers: sweater and light jacket recommended.
- Autumn Foliage: Mid-November to early December is peak season for autumn colors in the Izu Peninsula, particularly in interior areas like Shuzenji. The scenic drive to Dogashima becomes spectacular with fall colors. 🔗
- Crowd Levels: November is popular for domestic travel due to comfortable weather, but generally less crowded than peak summer holidays. Weekdays are noticeably quieter than weekends.
- Photography Conditions: November's lower sun angle may affect the intensity of light beams in the cave. Late morning to early afternoon still provides the best illumination. Cooler temperatures create clearer atmospheric conditions for coastal photography.
Best Time for Skylight Effect:
- Late morning to early afternoon (10 AM - 2 PM) provides the most dramatic light through the skylight, as direct sunlight creates the most intense beam and vibrant blue-green water colors
- The light's appearance varies throughout the day, with colors shifting from emerald to cobalt blue depending on sun angle
Best Photo Spots:
- Inside the Cave (Boat Tour): Focus on the column of light hitting the water - capture the vibrant color contrast with dark cave walls. Use faster shutter speed to compensate for boat motion. Look up through the skylight for dramatic framing showing the circular opening.
- Cliff-Top Viewpoint: Unique perspective looking down through the skylight. Capture boats passing below for scale. Wide-angle lens recommended for capturing the full coastal panorama.
Crowd Avoidance Strategies:
- Visit on weekdays rather than weekends
- First departure (8:15-9:00 AM) or late afternoon tours (after 3:00 PM) have fewer passengers
- Tours depart frequently (every 10-20 minutes), so even if one boat is full, the wait is minimal
- No advance reservations required - purchase tickets near parking lot or pier
Weather and Seasonal Preparation:
- Check weather forecast and call ahead (+81-558-52-0013) if conditions are questionable
- Tours cancelled during high waves or storms - no refunds, but alternate timing possible
- November weather generally stable, but Pacific storms can occur
- Bring wind-resistant jacket for open-air boat ride
- Non-slip shoes recommended for walking trail
On the Boat:
- Be mindful of other passengers - don't stand suddenly or block views for extended periods
- The experience is shared; quiet appreciation is the norm
- Follow captain's instructions during cave navigation
- Secure loose items in windy conditions
Nearby Attractions:
- Koganezaki Park (10 minutes by car): Dramatic coastal cliffs with "horse head rock" formation, potential Mount Fuji views on clear days, excellent for sunset viewing 🔗
- Futo Coast (2.5 km northwest): Unique magmatic dikes and volcanic formations, beach relaxation 🔗
- Sawada Park Open Air Bath: Ocean-view onsen experience, 9:00 AM - 6:00 PM (Oct-Feb), ¥600, closed Wednesdays 🔗
Integration with Other Locations: Dogashima serves as an excellent addition to a western Izu coastal itinerary and can be integrated with:
- Shuzenji Onsen: 90 minutes north, famous hot spring town with autumn foliage in November
- Shimoda: 1 hour south, historic port town with black ship history
- Mount Fuji region: 2-3 hours northeast via scenic Route 136
The location works well as either a day trip destination or overnight stay, particularly when combined with the scenic coastal drive and multiple Nishiizu attractions within 10-15 minutes.
Location: View on Google Maps
Source: attractions/izu-peninsula/dogashima.md