You can’t fly to Okinawa every time you need to get wet. The good news: two hours from Tokyo there’s a training bay where you surface facing Mt. Fuji — Osezaki on the west coast of the Izu peninsula, home base of the Kanto freediving scene.
Why Osezaki
- The topography is perfect: the cape wraps around like an arm, sheltering an inner bay that stays calm even when the open coast is blown out — year-round trainability that almost nowhere else in Honshu offers
- Real depth: a gentle slope runs from 5 m platforms down past 20 m — ideal for setting a line
- Life that surprises: soft coral gardens, seahorses, autumn sardine storms, and the occasional legendary sunfish
- The Fuji moment: on a clear day you surface to a full view of the mountain. Worth the train fare alone
When to come
| Months | Water | Wetsuit | Notes |
|---|---|---|---|
| Apr–Jun | 17–21°C | 5mm | Visibility recovering, few people |
| Jul–Sep | 22–26°C | 3–5mm | Most comfortable; go on weekdays if you can |
| Oct–Nov | 20–23°C | 5mm | The hidden ace: clearest water, sardines, sunfish |
| Dec–Mar | 15–17°C | 5mm + hood | For the committed; peak visibility |
Rule of thumb: Izu’s water runs one season behind the air. Don’t let a warm May afternoon fool you — the sea is still in early spring.
Getting there
- Train: Shinkansen Tokyo → Mishima (50 min), then the Izuhakone line to Shuzenji and a bus or taxi to Osezaki. About 2.5 hours door to door
- Drive (recommended): Tomei expressway → Numazu IC → the west-coast road. About 2 hours from Tokyo, and the coastal road is a destination in itself
- With gear, drive or ride with your school
After the dive
The correct Izu formula is diving + onsen. Stop at Shuzenji Onsen on the way back, or hit Numazu’s seafood market. Leave Friday night, train Saturday and Sunday, soak, and be back in Tokyo by Sunday night — the standard Kanto freediver weekend.
Can beginners come?
Yes. The bay’s calm conditions are actually better for coursework than many tropical islands — our AIDA2 course runs here. Just set expectations: the water is Honshu green-blue, not Okinawa neon. For training value and access, though, Izu wins.
Want to plan an Izu training weekend? Talk to us.