One of Tokyo’s best-kept secrets, Kozushima is a little-visited island getaway 45 minutes by plane or a minimum of 4 hours by boat from the city and is fast becoming known as one of Japan’s top stargazing destinations. It is one of the Izu Islands, a chain of volcanic islands stretching south-east from the Japanese mainland, all administered by Tokyo and forming part of the expansive Fuji-Hakone-Izu National Park. While a number of the islands are popular tourist destinations during the summer months, Kozushima remains relatively undiscovered and yet offers a wealth of attractions and activities for intrepid travelers.
Dark Nights and Starry Skies
Kozushima is the perfect place for stargazing, mainly thanks to a number of sustainable development goals (SDGs) which have been introduced on the island to preserve its spectacularly dark night-time skies. Named in 2020 as an International Dark Sky Park, Kozushima is only the second place in Japan to receive such a designation (the first being Iriomote-Ishigaki in Okinawa), and the local municipality has worked hard to reduce light pollution to almost zero. Luckily Kozushima was able to tick all the right boxes, and so was awarded the prestigious designation instead. Much work was still required to become a DSP however. This included refitting streetlights with hundreds of new, warmer-toned LED lights which emit no light skywards and garnering the ongoing support and involvement of the local community in coming together to help preserve the island’s dark skies for the future generations. But the locals have fully embraced the project, and are rightfully proud of Kozushima becoming an internationally-recognized Dark Sky Park. Apart from the obvious advantages for stargazing, the islanders’ efforts have reaped a whole host of sustainable benefits including significant energy savings, and perhaps most remarkably, the return in 2021 of nesting green sea turtles to Maehama (Kozushima’s main beach), quite likely as a result of the island’s more natural dark skies. As a visitor, it’s both moving and inspiring to see a successful project like this firsthand.
When it comes to stargazing, some of the best spots around Kozushima include Yotane Square, an easily accessible park nestling above the main village, and Akasaki walking path, a coastal boardwalk offering seaside shots and sunsets in the north of the island. But in truth, almost anywhere on Kozushima is great for practicing those nighttime photography skills, and knowledgeable locals such as Wataru Furuya of Full Earth Nature Guides will happily take you to all the best locations and point out the amazing array of stars, planets, and galaxies visible in the skies above. I even had a chance to witness the rare evening spectacle of a ‘moonrise’—when the moon takes on an orange sun-like glow as it peaks low over the horizon—a truly unique sight and an experience I will never forget!
Seaside Surprises and Mountain Highs
While stargazing may take up most of your time during the hours of darkness, there are plenty of things to do during the daytime on Kozushima too. Firstly, you can’t miss the island’s stunning beaches. Maehama is next to the main village and is a great surf spot, while over on the east side of the island at Tako Bay you can enjoy beautiful white sands and turquoise waters beneath spectacular crumbling cliffs; here you can also find Tako Spring, offering fresh and delicious drinking water right next to the beach! 
Other popular marine activities include fishing and diving, and at the Kozushima Hot Spring Recreation Center, you can relax in the warm open-air baths as you listen to the lapping waves and gaze out to sea (swimming costume required). At the end of a long day, this was simply the perfect way to unwind in the evening.
Highly recommended is the half-day hike up to Mt. Tenjo; the scenic summit area has numerous paths leading to panoramic viewpoints, with the other nearby Izu Islands and even distant Mt Fuji visible if the weather is fine. The summit plateau is also home to a number of intriguing natural features such as the heart-shaped Fudo Pond, and two white sandy desert-like areas which look like the surface of the moon! I have hiked all over Japan but was greatly surprised to see such varied and beautiful environments, especially on a relatively small mountain like this.
There are two main routes up the mountain with parking and restrooms at both trailheads; from the 6th station, the Shiroshima trail is a little shorter and easier, while the Kuroshima is a slightly longer approach (and if you don’t have a car then it’s possible to walk up from the village to Kuroshima trailhead in about 45 minutes)—however if you walk from the first marker on the Shiroshima trail it ends up being longer than the Kuroshima. While it takes a bit of effort to reach the top (bring some sturdy footwear), the breathtaking views and varied landscape of Mt. Tenjo make it all worthwhile.
After all that exertion, you may need a bite to eat, and there are a number of excellent options on the island. Down by the seafront, Cafe & Diner AILANA is known for some of the tastiest burgers in town. Alternatively, head to the harbor and feast on superb fresh and affordable seafood at Yocharre Center (よっちゃーれセンター), or perhaps sample the wares at Hyuga Brewery, Kozushima’s only craft beer brewery (and bar).
Why Kozushima?
If you want a quiet and relaxing seaside retreat, with amazing views, great food, and hardly any crowds, all in a place with environmental and sustainable sensibilities and just a few hours from central Tokyo, then Kozushima is a fantastic choice. Just don’t forget to bring your camera and a tripod for those starry nighttime shots!
Practicalities
Despite its slightly out-of-the-way location, getting to Kozushima couldn’t be easier; there are direct daily flights to and from Tokyo’s Chofu Airport (45 minutes) and regular sailings from Takeshiba-sanbashi in Tokyo on either the high-speed jet ferry (3hrs 45mins) or the overnight ferry (11 hours 55 minutes).
Once on the island, you can rent a car, motorcycle, or bicycle, and the village bus covers most of the main sights.
Kozushima has a number of accommodation options but perhaps the best is Vacation House Familia, a cozy B&B and cafe/bar run by a friendly English-speaking couple who will help you feel immediately at home on the island — you can even stargaze from the rooftop balcony!
Come to Kozushima, the best place in Tokyo to enjoy spectacular starry skies!
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