Iseki Point (Yonaguni Monument)
与那国島海底地形（遺跡ポイント）24°26′ N 123°01′ EDiveDive: advanced
Iseki Point is the dive site off Arakawa-bana on Yonaguni's south coast where a local diver found the stepped underwater rock formation called the Yonaguni Monument in 1986, about 25 m deep at its base and reached by dive boat or semi-submersible from Kubura.
Kihachiro Aratake found the formation in 1986 while scouting dive sites, named it Iseki (ruins) point because it reminded him of Inca stonework, and it has drawn divers since newspapers took it up in 1995. It spans about 250 m by 150 m, with flat terraces and sheer walls dropping some 25 m from the surface. Ryukyu University geologist Kimura Masaaki has argued since the 1990s that people shaped it. Most specialists in marine archaeology and landforms read the steps as natural jointing in the sandstone, and Okinawa Prefecture has not recognised it as an archaeological site.
Divers go down with a local shop, often in strong current, and Sawes Yonaguni also takes snorkellers over the site. For everyone else the Jack's Dolphin semi-submersible, skippered by the man who found it, leaves Kubura at 12:00 for about an hour, ¥7,000 for adults, paid in cash on board.
Before you swim
- Currents over the site can run very fast; Wikipedia's article calls it a site for advanced divers, though beginners can see it in some conditions.
- From June to September the south wind often stops boats reaching the south-coast site.
December to March
Winter is the better season for the site: the north-north-east wind leaves the south coast in the lee, and the Jack's Dolphin operator warns that June to September south winds can stop trips. Sawes Yonaguni gives water of 22–23 °C from January to April and advises a 5 mm suit.
Diving · advanced
A stepped sandstone formation about 250 m east–west and 150 m north–south with a height difference of about 25 m, its base around 25 m down and its top reaching close to the surface; terraces and straight walls.
Dive with a local shop.
Our ratings
- Scenery
Worth knowing
- Book the semi-submersible by phone the day before; the operator answers most easily in the evening.
- Take your usual seasickness remedy for the run round the island; the operator warns the boat can roll.
FAQ
Quick answers about Iseki Point (Yonaguni Monument)よくある質問
How deep is the Yonaguni Monument?
Its base lies about 25 m down, and its upper terraces come close to the surface. The formation measures about 250 m by 150 m with a height difference of about 25 m.
Can non-divers see the Yonaguni Monument?
Yes. The Jack's Dolphin semi-submersible sails from Kubura port at 12:00 and lets you view the formation through windows below the waterline; it costs ¥7,000 for adults (2026).
When is the best time to see the Yonaguni Monument?
Winter. The site lies off the south coast, and the operator warns that south winds from June to September often stop boats reaching it.
Is Iseki Point (Yonaguni Monument) worth visiting in winter?
Winter is the better season for the site: the north-north-east wind leaves the south coast in the lee, and the Jack's Dolphin operator warns that June to September south winds can stop trips. Sawes Yonaguni gives water of 22–23 °C from January to April and advises a 5 mm suit.
Is Iseki Point (Yonaguni Monument) safe?
Know these before you swim at Iseki Point (Yonaguni Monument): currents over the site can run very fast; Wikipedia's article calls it a site for advanced divers, though beginners can see it in some conditions; from June to September the south wind often stops boats reaching the south-coast site.
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