Stargazing at Kozushima: how dark is Tokyo's dark sky island?

Kozushima, a small island administered by Tokyo about 180 km south of the city, became Tokyo’s first International Dark Sky Park in 2020. It is the closest certified dark sky to Tokyo: about four hours by boat or 30 minutes by air, then a night with a Milky Way that the city never shows.

Why is Kozushima so dark?

In May and June 2020 the village replaced more than 400 street and road lights with dark-sky-friendly fixtures, according to DarkSky International. The whole village area, 18.58 km², is certified. The lights in the village are dimmer on purpose, and that is part of the point.

How to prepare for stargazing at Kozushima

• Transport: ferries and flights depend on sea and weather. Leave slack in your plan and check the timetable on the day.
• Darkness: with fewer streetlights, walking at night needs a red light and care on uneven ground.
• Weather: island wind makes clear nights feel colder than the forecast suggests. Bring a windproof layer.
• Moon: a trip around new moon is worth planning for, since you can’t nip back next weekend.

The stargazing trip checklist has the full packing list.

Sky Map (my app) works offline for the core sky map and its astronomical calendar lists meteor showers, so you can line up a trip with one.

Other dark skies in Japan: Ishigaki and Iriomote, Bisei. For city nights, see stargazing in the city.

Sources: DarkSky International Kozushima place page (darksky.org), Kozushima Village certification notice (vill.kouzushima.tokyo.jp), checked 2026-10-27.