Mayotte and its lagoon

Diving sites

The coral reef developed around the island at the end of its volcanic formation 1.5 million years ago.

During the last great ice age, 20,000 years ago, the lagoon thus formed was completely emptied by a drop in sea level of over 100 metres, causing the reefs to emerge.

As a result, the island’s rivers, held back by the reef, broke through the passes in the barrier.

Around 9,000 years ago, as the earth’s climate warmed, the rising waters returned to the top of the ancient reefs, and the corals began to grow again, building our playground, the coral reef we know today.

The passes are zones of water circulation, of exchange of water masses between the lagoon and the Mozambique Channel. These areas are therefore subject to strong currents, bringing together both reef and pelagic underwater life.

Because of this density of life, we prefer to dive in these particularly rich zones, without neglecting the outer slope of the barrier where we have discovered sites of interest in terms of underwater flora and fauna, but also from a geological point of view, such as large overhangs or even cavities created by the erosion of the reef when it was emerging, allowing us to travel back in time.

Passe Bateau

This pass, the closest to the center, is about 10 kilometers from N’Gouja beach, and takes about 25 minutes to navigate.

In this pass, we dive on both sides, south and north.

Plongée Dérivante

North side

On this site, whatever the current in the pass, we always start on the outer slope.

Here we find the first drop-off, a steep slope leading at around 35 meters to a sandy beach dotted with coral islets, home to fish and other small crustaceans.

This fifty-metre-wide sandy step descends gently to a depth of 45 metres, where we find a second, very vertical drop-off leading to depths reserved for divers specializing in Trimix diving.

This outer part of the reef is distinguished by the sheer quantity of fish we can encounter, from schools of lutjans and oriental diagrams on the vertical points of the first drop-off to jacks and other pelagic species on the edge of the second, colonized by numerous barrel sponges and gorgonians, not forgetting stingrays and a carpet of heterocongers on the sandy step.

Diving along the edge of the second drop-off may provide an opportunity to observe a few sharks, coral sharks or grey reef sharks, or even hammerhead sharks at the time of year when the masses of fresh water rise to the surface.

Once the current has returned to the pass, we make our way through an undulating landscape lined with soft corals, leading to the inner reef drop-off on the lagoon side, where we finish the dive in search of smaller coral-dwelling organisms.

South side

The verticality of this site is very marked, from the edge of the plateau at around 5 meters to 35 meters, rich in sponges, hard corals such as tubastreas, as well as numerous octocoralliarids up to 15 meters and beautiful gorgonians.

In the 15-metre zone, the drop-off is marked by a succession of large alcoves where, in addition to the numerous shrimps surrounding moray eels, we can observe a lot of small fauna such as nudibranchs, flatworms, not forgetting more mimetic fish such as scorpion fish or leaf fish.

Further down, from 30 to 35 meters, deep overhangs where it’s not uncommon to observe stingrays on the sandy bottom.

Then we find a slight slope leading to a large sandy plateau at around 40 meters, above which, depending on the current, a school of small barracudas can be seen in great numbers.

This dive has a few surprises in store: the 16/9 cave, a cavity cut into the wall at around 26 meters, whose 4-meter-wide, 1.5-meter-high entrance opens onto a large room in the reef. In strong currents, it’s not a good idea to neglect the blue, where a few pelagic species, such as the grey reef shark, may grace us with their curiosity. It’s also on this site that, in season and with a favorable current, we can observe manta rays of the alfredi genus feeding on plankton below the surface.

Bouéni pass

This very wide pass, a little further away at around 13 kilometers from the center, offers 2 totally different sides, both in terms of atmosphere and the life to be found there.

Plongée Dérivante

North side

This dive is carried out on a coral development at the end of the pass that characterizes this site. Approximately 150 meters long, this formation rises to a dozen meters and is located in the axis of the Bouéni pass.

We dive here on the outer slope, on the seaward side. To the south of this development, the drop-off leads to a sandy plateau over 35 meters, where we find beautiful spuds colonized by numerous branching corals and surrounded by schools of jacks and lutjans. Pelagic species such as tunas and yellowtail barracudas, and even a few sharks, can usually be seen as we move further out towards a second drop-off rich in gorgonians, from 45 to 80 meters.

Then, heading north, the drop-off becomes more pronounced, descending directly to around 60 meters. This part is very fishy, with schools of fusiliers and blue triggerfish in great numbers, which can be the object of trevally hunts. On this stretch, we regularly observe a massive shoal of black-tailed barracuda, giving the site its name, “the barracuda potato”.

Then we come to a wide canyon with a sandy bottom that rises gently from 35 meters to around 15 meters, allowing us to reach the reef and finish the dive surrounded by reef fish.

South side

This dive takes place entirely on the slope of the pass. It has two distinct sections.

Firstly, the eastern zone, on the lagoon side, is a large slope with a succession of sandy beaches from 40 meters between promontories, ancient recolonized coral formations, to a plateau over some ten meters where we find a decor of numerous pinnacles supporting developments of acropores illuminated by the sand lining the bottom.

This very bright part of the dive is rich in gorgonians, around which we can observe numerous shrimps and nudibranchs. Schools of black snapper and paddle snapper in large numbers criss-cross this area, sharing it with swarms of blue triggerfish.

The western zone of this site is vertical from 4 meters up to 15 to 25 meters depending on location. This drop-off leads to a large slope descending to over 45 meters.

Continuing the life we find further east, we find large numbers of gorgonians in this zone.

The vertical drop-off is remarkable for the number of fauna that inhabit it. Numerous soft corals, sponges and cnidarians have developed here, sheltering a whole array of reef fish, butterfly fish, angelfish and various damselfish, as well as numerous nudibranchs and flatworms, making it a delight for naturalist divers.

Small cavities are inhabited by hatchetfish and glass fish, forming curtains behind which it’s not uncommon to find leaf fish.

Sada pass

On this pass, our most remote site 15 kilometers from the center, we only dive on the north side. This dive takes place on the pass’s drop-off.

Vertical drop-offs

The first, on the outer side of the pass, drops to 55 meters. In the 15-25 meter zone, there is a succession of overhangs that make this dive very entertaining. Here we find numerous moray eels accompanied by cleaner shrimps. We are often accompanied by a large school of fusiliers.

On the bottom, at 55 meters, large boulders form a vast labyrinth in which magnificent gorgonians have developed, some exceeding 2 meters.

Heading towards the lagoon, the drop-off curves into a small bay. At this point, the vertical part descends to 20 meters, then an inclined slope reaches 50 meters. At the foot of the vertical section, a succession of small cavities reveal a wide variety of shrimp, nestling behind the soldier fish.

This bay ends in a fish-filled point opening onto the second drop-off of this dive, from 5 to 40 meters, where we find the same scenery of overhangs in the 20-meter zone and large gorgonians.

Lagoon dives

On this pass, our most remote site 15 kilometers from the center, we only dive on the north side. This dive takes place on the pass’s drop-off.

Vertical drop-offs

These dives take place on the inner reefs of the lagoon, about ten minutes by boat.
The coral gardens here are particularly well developed, allowing us to admire an incredible diversity of coral species, as well as a large number of crustaceans and nudibranchs in astonishing shapes and colors, to the delight of naturalist divers and photographers alike.

Chira Lepoe

On this reef, we dive around a point. From a sandbar surrounded by a coral garden rich in branching and leaf corals, we access the outer slope of the point.

This coral slope descends to 25 meters to join a sandbank that gradually drops to around 40 meters. From this drop-off, a succession of patates, more exposed to the current, gather a few shoals of fusiliers and support some beautiful gorgonians.

Rounding the tip of the point, we arrive in the “pool” formed by the point and the reef. Ranging in depth from 20 to 6 meters, the bottom of this part of the site is strewn with coral spats where we can find a few lobster nests.

Chira Rani

This vast reef offers several dive sites, mainly on its western side.

We anchor on sandbanks that we’ve named according to their respective characteristics and dive on drop-offs leading from 15 to 25 meters, with the possibility on some sites of moving away from the drop-off to visit the numerous patates pausées on bottoms of around 30 meters, some of which go up to a dozen meters.

We end these dives by taking the time to search the coral gardens on the edge of the flat at around 5 meters, to unearth a few specimens of shrimp or nudibranchs.


It’s a very small reef that can be circumnavigated in one dive. From the plateau at 4 meters, a drop-off of up to 25 meters starts, at the foot of which are large boulders covered with black corals and polyps of various colors, creating an atmosphere of multicolored nebulosities.

Forming a labyrinth, these boulders are heavily colonized by fixed fauna, including a large number of nudibranchs.

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    Le Lagon Maoré
    Plage NGouja Kani Keli BP636
    Chirongui 97620

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