Chiba south · TateyamaNo.106★Open in map →
Okinoshima
— the walk-to island at Tateyama's tip
A small wooded island in Tateyama, Chiba, joined to shore by a 200-metre sandbar you can cross on foot — one of the northernmost places in Japan where coral grows.
Okinoshima is a wooded islet, roughly a kilometre around, tied to the Boso coast by a narrow strip of sand. The island is uninhabited and covered in warm-temperate coastal forest. Its clear shallows draw swimmers and snorkellers through the summer season, and the far shore is a quieter spot for hunting shells and sea glass. Walking the whole loop of the island takes about half an hour.
Why it stays quiet
Most people stay on the swimming beach and never walk round to the quiet back shore or the small shrine in the trees. There is little English information about the island, and it sits off the main tourist route out of Tokyo, so the far side stays calm.
Background & history
The island reportedly sat about 500 metres offshore until the 1923 Great Kanto Earthquake lifted the land here. Later sand build-up tied it to the coast, forming what geographers call a land-connected island. A shrine on the island is dedicated to Ukanomitama, a Shinto deity of grain and food, and the whole area is protected within Minami-Boso Quasi-National Park.
What to look for — in walking order
- The sandbar crossing
- roughly 200 metres of exposed sand linking the mainland to the island, walkable when the tide is low
- Old coastal forest
- warm-temperate woodland, with some trees reported to be over 300 years old
- Northernmost coral
- the shallows here cited as one of the northernmost places coral grows in Japan
- Island shrine
- a small Shinto shrine to Ukanomitama, tied to local tales of white serpents and good fortune
How to enjoy it
Cross when the tide is low, so the sandbar is exposed. A slow loop of the island takes about half an hour; the far shore is the place to look for shells and sea glass. In high summer, earlier in the day is calmer before the beach fills up.
How to actually get there
- Tokyo Stn → Tateyama Stn (Boso Nanohana highway bus, direct, ~2 hr)
- Tateyama Stn East Exit → last stop (Nitto Bus, Tateyama Aviation Corps line, ~15 min)
- Bus stop → Okinoshima beach (walk, ~20 min)
- Cross the sandbar on foot and loop the island (~30 min)
- Highway bus + local bus
- Tokyo Stn (Yaesu South Exit) →(Boso Nanohana highway bus, direct, ~2 hr)→ Tateyama Stn →(Nitto Bus, Tateyama Aviation Corps line from the East Exit, ~15 min)→ last stop →(walk, ~20 min)→ Okinoshima. Total about 2.5 hr. The local bus runs about once an hour; the highway bus needs a reserved seat, so book ahead.
- Return
- The local bus back to Tateyama Stn runs about hourly and services end in the early evening. Check the return times on the timetable at the stop when you arrive, before you walk to the island.
Before you go
- Cash
- There are no shops on the island. Rural buses are often cash-only, so carry coins and bring water and any cash you need from town.
- Closing days
- Check the tide first: cross when the water is low and head back before it rises. This is a protected park, so take nothing living.
- Another way
- A taxi from Tateyama Station reaches the beach car park in about 10 minutes if the bus times do not suit you.
- After you get off
- From the last bus stop it is about a 20-minute walk to the beach. From the beach, walk out along the sandbar, then loop the island clockwise.