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Hotels, dive operators, gear, and how to get here are on the Ogasawara location page.
Overview
In-water encounter with resident pods of Indo-Pacific bottlenose and spinner dolphins along the western and southern coasts of Chichijima, the main island of the Ogasawara (Bonin) archipelago — 1,000 km south of Tokyo and accessible only by a 24-hour overnight ferry from Takeshiba. Boats spot pods from the surface, then drop snorkellers ahead of the line of travel. Bottlenoses are slow, curious, and often hold eye contact for whole passes; spinners move in larger, faster schools and frequently spiral past at 5–10 m. The surrounding reef hosts the wrought-iron butterflyfish (Chaetodon daedalma), a species endemic to southern Japan that is unusually common here. The Ogasawara group is a UNESCO World Heritage Site (2011), often called Japan's Galápagos for its isolated endemic fauna.
Briefing note
This is a wild-pod encounter, not a captive interaction; sightings are weather- and mood-dependent. Tour operators follow strict approach rules — no chasing, no touching, drop in front of the line of travel. Summer (June–September) is the most stable window but coincides with typhoon season; winter (January–April) brings humpback whales but cooler water and rougher swell. Allow buffer days at either end — ferry sailings cancel for weather and there are no alternatives.
What you'll see
7 species curated- year-roundIndo-Pacific bottlenose dolphin
- year-roundSpinner dolphin
- seasonalHumpback whalePeak: Jan · Feb · Mar · Apr
- seasonalSperm whalePeak: Jun · Jul · Aug · Sep · Oct
- year-roundWrought-iron butterflyfish
- year-roundGreen turtle
- seasonalDogtooth tunaPeak: Apr · May · Jun · Jul · Aug · Sep
Sightings evidence
1 record on file- high confidenceIndo-Pacific bottlenose dolphin
- Last confirmed
- Sep 2025
- Recent records
- 65 within 50 km
Sources & methodology
How we summarise this
We aggregate confirmed occurrence records from GBIF and OBIS within a fixed radius of each dive site. Occurrence records confirm presence and reveal seasonality clustering, but they DO NOT measure per-dive probability — there is no eligible-effort denominator. We deliberately do not publish a numeric '% chance of sighting' from this data.
Sources
- Global Biodiversity Information Facility — GBIF Secretariat
- Ocean Biodiversity Information System — IOC-UNESCO
- iNaturalist — California Academy of Sciences & National Geographic Society
- OBIS-SEAMAP — Duke University Marine Geospatial Ecology Lab / OBIS
- IUCN Red List of Threatened Species — International Union for Conservation of Nature
- WoRMS — World Register of Marine Species — Flanders Marine Institute (VLIZ)
- FishBase — FishBase Consortium
- Atlas of Living Australia — CSIRO / GBIF Australia
- REEF Volunteer Fish Survey — Reef Environmental Education Foundation
Conditions
| Month | Water | Visibility | Current |
|---|---|---|---|
| Jan | 21–23 °C | 20–30 m | mild |
| Feb | 21–22 °C | 20–30 m | mild |
| Mar | 21–23 °C | 20–30 m | mild |
| Apr | 22–24 °C | 20–35 m | mild |
| May | 24–26 °C | 25–35 m | mild |
| Jun | 26–28 °C | 25–40 m | mild |
| Jul | 27–29 °C | 30–40 m | mild |
| Aug | 28–29 °C | 30–40 m | mild |
| Sep | 27–29 °C | 25–35 m | moderate |
| Oct | 25–27 °C | 20–30 m | mild |
| Nov | 24–26 °C | 20–30 m | mild |
| Dec | 22–24 °C | 20–30 m | mild |
Season calendar
Peak season highlighted · current month outlined
Gear for this site
Beyond the basic kit- Long freediving fins — The dolphins set the pace. A few extra seconds of speed on the kick is the difference between a full pass and watching them disappear.
- Snorkel and mask (no scuba) — By prefecture rule and pod behaviour, encounters are snorkel/freedive only — bubbles drive the dolphins off.
Next step
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