Blue Lagoon
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.
The Blue Lagoon is Rangiroa's excursion rather than a dive: a pool of impossible aquamarine sealed inside the atoll's southwestern rim, reached by a boat crossing that is half the experience. The water rarely tops a few meters, which is exactly why it glows. Blacktip reef sharks cruise the shallows in numbers — juveniles nursery here — sharing the flats with mullet, rays, and confident snapper while frigatebirds and noddies work the motu behind. Tours add a motu barbecue and time to wander sandbars. Divers should file it honestly under rest-day magic: fins, mask, and no tank required or wanted.
The moment you come for: Blacktip reef sharks in gin-clear shallows; the aquamarine pool and its bird-loud motu; a classic Tuamotu day out.
Topography: A natural lagoon-within-the-lagoon: sand flats and coral patches enclosed by a ring of motu
Entry: A day-trip crossing of about an hour to the atoll's far southwest rim; visits wade and snorkel the shallow pool and its motu.
Know before you splash
Hazards: Sunburn and coral cuts top the list; the crossing gets rough in wind and trips cancel in bad weather.
Conservation: The shallows are a shark nursery — wade calmly, feed nothing, and follow guides' instructions around resting animals.
Who you'll meet
Blacktip Reef Shark
Green Sea Turtle
Porcupinefish
For photographers
Wide angle: ★★★★★ · Macro: ★☆☆☆☆ — editors' 1–5 rating of what this site gives each style of shooting