Mikomoto Island
Depth is the range from the top of the site to its usual maximum; "recommended cert" is the mainstream-agency level operators usually ask for, not a legal rule. Currents and visibility change daily — treat everything here as planning ranges.
Mikomoto is a lighthouse rock nine kilometers off Shimoda where the Kuroshio delivers the goods: from early summer into autumn, scalloped hammerheads school in the flow, and the standard dive is a brisk drift along the ridges scanning up-current until the silhouettes assemble. Schools range from polite handfuls to processions that take minutes to pass. Amberjack and rays ride the same conveyor, and the rocks themselves wear a hardy crop of soft coral. This is Izu's serious dive, with real current, real blue-water discipline, and rewards sized to match; local shops vet experience levels for good reason.
The moment you come for: Hammerhead schools within sight of Honshu, energetic Kuroshio drifts, big-fish traffic
Topography: Current-swept rock ridges and boulder slopes falling into blue water
Current: The Kuroshio's edge washes the rocks; currents shift mid-dive and the guides read them constantly.
Entry: Boats run from Shimoda to the lighthouse rocks offshore; negative entries and group drifts are standard, and marginal weather cancels quickly.
Know before you splash
Hazards: Strong shifting current, exposed offshore position, and depth creep while shadowing schools; surface markers required.
Nitrox: Worth it here — profiles sit in the range where enriched air meaningfully extends no-stop time (with the training to use it).
Who you'll meet
For photographers
Wide angle: ★★★★☆ · Macro: ★☆☆☆☆ — editors' 1–5 rating of what this site gives each style of shooting