Yonaguni Monument

Verified2026-09-11 checkedWallDrift

A terraced rock formation off Japan's westernmost island, and a winter hammerhead site.

Depth: 5–27 m16–89 ft
Difficulty: Advanced
Entry: Boat
Typical current: Strong
Coordinates: 24°25.998′N 123°0.000′E
Activities: Scuba · Freediving

The Monument is a stepped sandstone formation off Yonaguni whose origin — natural or worked by people — is still argued about by geologists and archaeologists. Whichever it is, the diving is demanding: the Kuroshio current runs hard across the site and dives are timed and often aborted. In winter the same current brings schooling hammerheads to the island. Operators require logged experience and will refuse divers in strong conditions.

Flight from Naha or Ishigaki to Yonaguni, then boat from Kubura port.

Best season

ExcellentDec–Feb
GoodMar
FairApr–Jun
FairOct–Nov

Before you get in

A wall. There is no bottom in sight to judge against, so depth is kept by the gauge alone — and it is easy to end up deeper than intended.
Recorded as a site with strong current. Settle your gas reserve, when you would call the dive, and your surface signal before you get in.
A drift dive: you do not come back to where you went in, so boat pickup and an SMB are part of the plan rather than extras.

Taken from this site’s recorded depth, type and current, and nothing else. An empty list is not a safe site — the sea on the day, the local geography and the boat traffic are not in it. The briefing on the spot comes first.

Conditions

Water temperature: 28.8°C84°F
Wave height: 1.8 m6 ft
Air temperature: 25.4°C78°F
Wind speed: 28.8 km/h17.9 mph

Updated 2026-10-07 16:15 UTC · Source: Open-Meteo

Weather data by Open-Meteo.com (CC BY 4.0)

Conditions are reported for information only. Assess the site yourself and follow your guide and your training.

No live conditions for this site yet.

We only show numbers we can attribute to a source.

Sea state and tide

On a date

Tide · 10/8

High04:501.49 m
Low11:110.19 m
Low23:260.34 m

Forecast heights against mean sea level. Real tides in a bay, a harbour or over a flat can differ — check an official tide table before you get in.

Pick a day to see its tide

Only wave height and wind are scored, because those are what close a boat ramp or a shore entry. Water temperature is reported and never scored: 12°C is an ordinary dive in a drysuit and punishing in a 3 mm, and a number that cannot see your suit has no business marking it down. Stars do not decide whether you get in — you and your guide do, on the day.

Weather data by Open-Meteo.com (CC BY 4.0)

Marine life you may see

Scalloped hammerheadSphyrna lewiniDec–MarSeasonal
Green turtleChelonia mydasCommon
Giant trevallyCaranx ignobilisSeasonal
Bigeye trevallyCaranx sexfasciatusCommon
Giant morayGymnothorax javanicusCommon
Napoleon wrasseCheilinus undulatusSeasonal
TrumpetfishAulostomus chinensisCommon
Yellowfin tunaThunnus albacaresRare
Moorish idolZanclus cornutusCommon

From divers

What people who were in the water reported. Not a forecast, and not a judgement about whether the site is safe to dive.

No recent reports from divers. If you dived here in the last two weeks, you can say how it was.

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