Manuelita
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.
Manuelita is the islet guarding Chatham Bay and the closest thing Cocos has to a house reef - which at Cocos means hammerheads over the deep side by day and one of diving's great spectacles after dark. On the night dive, hundreds of whitetip reef sharks pour over the coral garden in a hunting wave, shouldering into crevices after sleeping fish while divers' lights track the melee. Tiger sharks, now regular at Cocos, cruise Manuelita's sand edge often enough that guides brief for them as a matter of course. The shallow garden also serves as the trip's gentlest dive, thick with morays and marbled rays.
The moment you come for: The whitetip night hunt, regular tiger shark passes, an easy coral garden in a hard place
Topography: Coral garden on the protected side, boulders and wall on the exposed side
Current: The sheltered inside works in most conditions; the deep outside corner catches flow and sharks.
Know before you splash
Hazards: Night-dive task loading amid large excited animals; tiger shark protocol per the guides.
Conservation: Night dives run under park protocols; lights and diver numbers are managed to limit disturbance.
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
Marbled Ray
Scalloped Hammerhead
Tiger Shark
Whitetip Reef Shark
For photographers
Wide angle: ★★★★★ · Macro: ★★☆☆☆ — editors' 1–5 rating of what this site gives each style of shooting