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surface water-air while diving

New Caledonia lagoon.The lagoon covers 23.000 square km and its length is 1600 km, without disruption. There are 350 varieties of coral and 2700 species of fish.

The reef is partially Heritage of Humanity (UNESCO), dated June 7, 2008 (meeting of Quebec). Six marine groups representing the main diversity of coral reefs and associated ecosystems in the archipelago of french are concerned : the reef d'Entrecasteaux, the great lagoon north, followed by a north-east coastal area, Ouvéa, a small west coastal area and the south lagoon. Some "buffer zones" (unclassified), were also drawn, dedicated to protecting the surroundings of areas classified  .

Polynesian lagoons. The most important lagoons of Polynesia are those of Tuamotu atolls, which virtually have no longer land in the middle. There is of course Rangiroa, but also some others settings for diving, as Fakareva. As in New Caledonia, there would also be 350 species of coral reefs.

The Australian Great Barrier covers a discontinuous area of  350,000 square km over 2000 km long (3000 reefs, more than 2000 islands), there are 500 varieties of corals).

The life would come from the sea, and us too (see daily physics ), there is perhaps 2.5 billion years or more, when these "fatty" molecules which had been formed like says one, "eyes (greasy drops) on the soup", became animated. Much later existed yet only microscopic algae and invertebrates, then increasingly large.

At (about !) -600 million years came then sponges, worms, trilobites, snails of sea, crinoïdes... ; then, (-500 million years) corals, nautilus and first vertebrate

At -450 million years, coral reefs develop on a large scale, plants appear on ground. Towards -400 million years, are the ancestors of current fish and sharks : it is "the age of fish".

On the ground, certain marine invertebrates start to adapt to the terrestrial life, having plants to nourish themselves, and oxygen. The ground starts becoming green and the first reptiles will arrive. But there would be yet a sole continent on the planet, gathering about all that we currently know. It will be dislocated only at -200 million years to form our continents floating on the magma, their "plates" being able to reach a 150 km thickness, the remainder making up of oceanic plates, much less thick. See "some more, top page"

In the whole Polynesia, in Australia (great corail reef), but mainly in New Caledonia, corals are nearly intact. There is nearly nothing left in Indian ocean (I saw some deseperate divers), in Asia, in Africa, in the Caraîbans excepted a few spots  (se "the coral", map).

So, let try yourself by a sail to an islet, even in the vicinity.If the colors of lagoons or the sand bank atolls are more appealing and like nowhere else in Polynesia, New Caledonia is surely in a better position for the corals ; its reef is there indeed often very distant and there are small islands rimmed by reefs or some "potatos" in the middle of the large lagoon. One can observe small groups within a metre of water or less, in Noumea, Bora Bora or elsewhere (see homepage hibis). Get goggles or diving, unless you too afraid to put his nose in the water because standing in the water, you can see a mini scattered coral, fish with a fish partner(s), and sometimes more, in a few one meter deep water of the public beach. Excursions marine and submarine are available if you have a little time and some money : sailing and motor, windsurfing, surfing windsurfing, water skiing - diving, trail submarine (islet Noumea), boats glass bottom , and even a "SP700" submarine (Bora Bora and Noumea, Dumbéa pass / lighthouse Amédée). I don't talk about fish feeding, it's your choice. A short flight is also a rare pleasure (plane, helicopter)

Formation of the lagoons

The islands of Polynesia come very from a " hot point " of the earth which at the time of its eruptions, has created the volcanos, thus making going up the ocean floor locally. Some did not go up to surface. The displacement of the oceanic plate towards the North-West makes that the same " hot point " creates a whole line of volcanos (archipelagoes).
Hawaii îslands "  are moving diagonally too, for the same phenomenon.

Through thousands of years, corals bordering the volcano at the beginning, turn out to corals reefs. Their growth compensate for the depression and the supplementary rise of water due to the thawing of glaciers. At the same rate, the lagoon enlarge itsel. When the volcano has completely desapparead, it's an atoll.

The depression of the grounds is expressed in million years whereas the increase of water due to the thawing of the large glaciers amounts in thousands of years. Even by combining both, the thawing of the glaciers during the last 15000/11000 years seems dominating in "the depression" of the coral (wich can reach a thickness of 300 meters deep).

In New Caledonia, islands are in the lagoon, and some are really very close, such as îlot Maître (Nouméa); dont deprive yourself of the short trip (although it might jump a bit on the boat). "The pontoon is a beautiful trip, but the Amedee lighthouse is to be preferred, in both cases, you will be close to the reef and a great day all-inclusive is a nice memory.
Islands of Polynesia (motu) are circulars alignments, cut by a bit of shallow water, componant of the reef. My brief experience do not allow me to say more, and possibilities must be seen locally. The most beautiful are generally "occupied" (private property or hotel). From there, unlike New Caledonia, you will see the fall fairly close (outside the lagoon, deep sea), where the corals are best prepared. There are fringing reefs on the edge of land or islands. The interior of the Polynesian lagoon is enchanting by its shades, but most often, it has a very limited life, if any.

The reef circle a lagoon whose part no facing the wind is larger than the other (say under the wind (sheltered). On the sheltered coast (the wind have to cross the island), slopes are attenuated but the sea receive less oxygen.

Lagoon of Raiatea, in its part that join two îslands. The reef of all Polynesian islands is set on the slopes of a former volcano (see "hibis, Polynesia"). It is the same for the  Melanésian islands Vanuatu, Hawaii or of  the Indian ocean.

New Caledonia has, in length, the larger lagoon of the world, but the Australian Great barrier is the first of the world. New Caledonia, no volcanic, is linked with Australia. A former land, theTasmantia, is now under the water.

Don't need to put your hat while reading this text, but once on the spot, don't forget it. it could be a big and painful mistake. Add some others body protection too. see information, "risks and dangers".

The lagoon extends between the island itself and girdles of limestone built by the corals, which still live close to surface ( generally in a few meters of water).

The thickness of this limestone belt can reach several hundred meters (see "The Corals"
It erodes and crumble with tempests and the time.
The reef circle a lagoon which is larger on the side protected from the wind (which has to cross over the island). On this side, slopes are lower too.


click : detail of motus (Bora Bora but they are all the same in Polynesia)

Lagoon of Bora-Bora, with its small islets (motus). Like all the islands of Polynesia, the reef was formed on the slopes of an old volcano. See formation.
It is also the case for the islands of Mélanésie (Vanuatu - ex New Hebrides), of Hawaii or of the Indian Ocean.

New Caledonia, surrounded with the more larger lagoon of the world, (not to confuse with the Australian Great Barrier, so famous too), is linked to Australia, nonvolcanic land. A former land that linked it to Australia, the Tasmantia, is now underwater..

The sun is not always shining and the lagoon not always a still lake then, it won't be plain sailing and you could can be shaked and "sprinkled" if the wind rises, even with a large boat. Always think streams could be dangerous, mainly near the passes. look at the tides charts (see " risks and dangers " at the bas and fondoc (true stories).

Nouméa. This day was a very fine day, like most often ; on the "ponton" (Nouméa), we could swim and dive nearby, on the next "patate" and look at the passe away,
Please, see also "the coral"

photos hibis 

Right hand, spectacle from a glass boat


  "sailing to the reef" (Nouméa)

The lagoon is not deep ; only a few meters to some tenths of meters.; there are sand banks and isolated coral solid masses and one can sail brutally from 23 meters to 10 or 2 meters.

External side, the slope is stiff and the depth encrease very quickly until the ocean floor (approximately 2000 to 4000 meters max) ..

The barrier reef testify of the real size the island had at the beginning ; so, New Caledonia was at least twice !   In the south of New Caledonia, the reef barrier ends the lagoon at more than 60 Km off the coast. See its corals (link "the coral" - of New Caledonia - this page, bas)

The Corals builders always do not form a lagoon : indeed, the reefs known as "fringing" are established at the  edge of the shore or next to. (Pines Island, NC)


In fact, reefs are edging the coast at the beginning, in shallow water ; it's only when the ground sink slowly that corals begin to built in high  (example, 3 cm a year).

 NC tourisme

The reef and the Boulari pass, 20 Km far away of Nouméa. The passes are due to the water stream of the rivers, the corals not being able to live in because of the softened and colder water, charged of impurities. These pass can be dangerous, according to the tide and it is advisable to get good information.


éditions Pétroglyphes ; barrier reef of New Caledonia

Amid the corals or in open water, the animal life of the lagoon is extremely rich.

It is incredible but when diving, all the fish disappear suddenly and one wonders where they could have been. Not in the protected area and especially in the " catering to fishes" for tourists (who interest only the voracious species).

No regular algae at the bottom of the lagoons ; algae of the reef, wich grow on the sea side are most often  calcified and hard like corals. There is no kelp either on the coasts or the beaches of the Pacific and the algae, which exist however, are odd or tiny : they are crawling on the sand of the small islands and inflate their faded small balloons as soon as water arrives and at the contrary are very often calcified and hard like corals on the reef, on the side facing the oceans. Short algae covers therefore dead corals like a dull moss. Right hand, Euchema algae which grows on the coral in some areas and kill it (Karibati, Ohau)

Motus in Polynesia, islets  in New Caledonia .
(to see : islands and Islets of New Caledonia) ; they are different each from other but all of them will give you a full feeling of profound happiness and I highly urge you going there even if it is in the vicinity, not really isolated and touristic. Don't miss it !
 Of course it's better going on the Paul Emile Victor's motu in Bora or on a private boat on an islet of New Caledonia not to much crowded in opening days, but go as you can.

Lagoon life 1 fish and reef vivid beings

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