Aldabra Island
CHART NO 2554

General Information

Topography:

Aldabra, the world’s second largest coral atoll, is in the Aldabra Group of Islands which includes the Island of Assumption and the atolls of Astove and Cosmoledo. Uninhabited and extremely isolated, Aldabra is virtually untouched by humans. It has a distinctive island fauna including the Aldabra Giant Tortoise and is declared as a world heritage site by UNESCO.

The atoll consists of a ring of four larger Island clockwise, they are Picard or west Island, Polymnie Island, Malabar or Middle Island and Grand Terre the South Island. Additionally, there are a large number of smaller islands and islets. The islands consists of limestone uplands which has a rugged surface generally covered with dense scrub. There is no permanent population other than the Island Manager, Research Officer, their rangers and staff at Aldabra. 
The research centre is situated on the southwestern tip of Ile Picard. The seaward side of the coral islets is steep and end abruptly, and there are numerous 
undercut caves beneath these coral islets.

Grande Terre is the largest island on the southern side of the atoll. All along the southern coast, Grand Terre is bounded by sandy shoreline while the side facing lagoon comprises of dense mangrove and shrub vegetation.

Ile Picard, situated at NW end of the atoll has a sandy coast on the western side and on the east is covered by shrubs. One can find ruins of old buildings in the northern side of this island. These few buildings are no more occupied by the research centre staff and remain in depleted condition.

Ile Malabar an island on the north of the atoll has continuous rows of trees at the eastern end of northern coast.

Polymnie Island lying between Ile Malabar and Ile Picard on the N side, completes the circumference of the atoll.

The lagoon of Aldabra Island contains mud flats and islets of which Ile spirit and Ile Michel are prominent ones. The bottom of lagoon is largely sandy. Grande Passé a channel which has sufficient depths is the only route to access this lagoon. Local knowledge and knowledge on tidal streams is necessary to navigate within the lagoon.

Depth:

The waters around Aldabra Island (09°25’ .00S, 46°20’ .00E) are deep and clear of charted dangers outside a narrow fringing reef which is steep- to except at the E end of the atoll.

Natural conditions: 

Tidal stream refer to chart no. 2521 for details of the tidal streams off the W coast of the Ile Picard.

Current:

In the vicinity of Aldabra Island, the W – going South equatorial current is of low to moderate constancy with an average rate of 1½  kn. In the early part of the year, however, this current may be temporarily replaced by a low constancy NE – going current with an average rate of 1¼  kn.

Tide levels:

Mean spring range is about 2.8 m; mean neap range is about 1.0 m. 

Directions:- 
Landmark:

Flag staff (09°24'.06S, 46°12'.36E)

Useful marks:

Ile Picard light (white beacon, red bands, 13 m in height)  (09°24'.06S, 46°12'.36E).
Flagstaff  (09°24'.06S, 46°12'.36E).

Anchorage:

In Dec 2011, Indian hydrographic Shiphas anchored in the area. A good anchorage was obtained on the NW corner of Ile Picard in position (09°23'.13S, 46°11'.921E)in about 52mtr depth.