Poindimié & Hienghène

Every dive here leaves from one dock. Tiéti Diving works out of the Hôtel Tiéti compound in Poindimié village, loads its 12-diver semi-rigid at the quay and runs two-dive mornings; the far sites, such as the four pinnacles of Natacha in the Bayes channel, are about 45 minutes out. The centre opens every day of the year except 1 January, weather permitting, and trips are postponed when the trade-wind coast is blowing. It runs what it says is the only multi-gas fill station on Grande Terre outside Nouméa, with free nitrox for certified divers and trimix, sidemount and rebreather support, so the trench-edge technical sites are dived from the same boat as the lagoon coral gardens.

The reef is a double barrier and each side dives differently. Inside it, Val d'Isère and Tignes are white-sand bottoms dotted with hard corals, linked by the staghorn-studded 'Vallée Blanche'. Outside, the diving is a chain of pinnacles thick with gorgonians and cut by canyons, arches and tunnels: Dahab de Nous links five of them through a long lit tunnel, and Zorglub's tunnels are packed with hatchetfish. Pygmy seahorses live on the sea fans at Pascaline, Waneck and Bargibenti, beside nudibranchs and orang-utan crabs. Off the pass mouth the bottom falls into the Poindimié trench: Tombant 60 shelves at 40 m and drops past 120 m; the Caverne d'Albi Baba reaches the trench ridge at 60 m.

The World Heritage listing applies here in a way it does not in Nouméa. The reef off Poindimié and Hienghène falls in the 'zone côtière nord et est', one of six zones inscribed in 2008 as Les lagons de Nouvelle-Calédonie, whereas the lagoon off Nouméa is named among those UNESCO did not recognise. From Pouébo to Ponérihouen the coast faces the prevailing winds, so it is wetter than the rest of Grande Terre, with forest on a narrow strip between the mountains and the sea. Near Hienghène the Hienga and Doïman islets are protected marine areas and habitat of a dwarf seahorse, with an underwater trail at Îlot Hienga.

This is a single-operator destination and should be planned as one. A diver here is booking with one small club and diving whatever its boat runs that morning, with no second centre to fall back on; a centre listed at Hienghène's marina has no confirmed name or evidence it still operates, so Manta Point and the Labyrinthe, about 16 km along the reef, cannot be counted on. It suits macro divers after pygmy seahorses, divers who want the listed north-east lagoon rather than the Nouméa side, and technical divers who want a trench wall with trimix fills on site. Divers wanting a choice of operators or a week of easy diving are better served by Nouméa's day-boat scene.