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Aldabra, part of the Outer Islands of Seychelles, is one of the largest atolls in the world. This immense nature reserve, with its exceptional biodiversity, can only be visited aboard expedition cruise ships. There are lots of snorkeling locations in the atoll, such as Passe Dubois, which can be explored by drift snorkeling. Gently drifting in the pass, you’ll have good chances to spot several species of sharks, sea turtles, and a lot of fish.

Potato grouper in Passe Dubois, Aldabra
A large potato grouper encountered on the pass slope.

How to get to Passe Dubois snorkeling spot?

Passe Dubois is located in Aldabra, an outer atoll of Seychelles located some 700 miles/1000 km southwest of Mahe and 220 miles/360 km north of Madagascar. Listed since 1982 on the UNESCO World Heritage List, it is one of the largest atolls in the world, and one of the last ecologically-intact places on the planet. Aldabra can only be visited during expedition-style cruises or with your own boat, after obtaining prior authorization from the Seychelles Islands Foundation.

Passe Dubois is one of a series of narrow passes that have formed on the west coast of Aldabra. Located about 700 meters south of Ile Picard, it is the deepest pass in the area.

Passe Dubois snorkeling map, Aldabra

Water entrance for snorkeling Passe Dubois

Passe Dubois is generally explored by drift snorkeling, gently carried by the current. You will be dropped off by zodiac at the entrance to the pass, and picked up on the other side (in a lagoon > ocean direction at ebb tide, and in an ocean > lagoon direction at flood tide). Follow the instructions of your guide.

Passe Dubois snorkeling exploration tips

The pass is permanently crossed by currents, which have an incidence on the development of corals. The seabed alternate between pretty coral formations (including branching coral, massive coral and uncommon black coral) and washed areas, covered with sand and polished coral.

Coral patch at Passe Dubois
Coral formation in Passe Dubois.

Located in Aldabra Atoll, Passe Dubois is home to an exceptional density and diversity of marine species. While exploring the area, you can see a lot of reef fish, including angelfish, surgeonfish, parrotfish and butterflyfish (see list of species at the bottom of the page).

School of spangled emperor at Passe Dubois
Spangled emperor schooling in the pass.

Large potato groupers dwell on the slopes, where large schools of spangled emperors and bluefin trevallies are also found. Passe Dubois is also visited by sharks, mainly blacktip sharks and lemon sharks (occasionally tiger sharks), as well as by hawksbill turtles.

Blacktip reef shark in Aldabra
A blacktip reef shark dwelling on the seagrass beds fringing the pass.

Restaurants and accommodation nearby

Aldabra has no amenities. Expedition-style cruises are all-inclusive.


  • Level required Advanced
  • Protected areaAldabra Atoll Special Reserve
  • Maximum depth30ft/10m
  • Water entranceFrom a small boat
  • LifeguardNo
  • Visitor numbersLow
  • Access costsAboard an expedition cruise ship
  • Restaurants nearbyNo

MAP Spot

These spots are only recommended to good swimmers, in good physical conditions, and with excellent snorkeling skills. These spots can experience currents, moderate waves, important depths, tight or narrow passages, or tricky water entrance, and can be located near hazardous areas (channels, boat traffic, strong currents…). The distance to swim to reach the most interesting snorkeling areas can be important - up to 500 meters. The “advanced” category includes drift snorkeling (transported by currents) and snorkeling off the coast.

This level only apply when the spot experiences optimal sea and/or weather conditions. It is not applicable if the sea and/or weather conditions deteriorate, in particular in the presence of rough sea, rain, strong wind, unusual current, large tides, waves and/or swell.You can find more details about the definition of our snorkeling levels on our snorkeling safety page.