Comoros, where’s that?

The islands of Comoros are a group of four volcanic islands situated in the  Mozambique  Channel in the Western Indian Ocean, halfway between the east coast of the African continent and the northern extremity of Madagascar. Three islands, namely Grande Comore (Ngazidja), Mohéli (Mwali) and Anjouan (Ndzuwani) have made up the independent Union of the Comoros since 1975,  while the fourth island, Mayotte (Maoré), falls under French administration.


Western Indian Ocean

Comoros archipelago


Anjouan - Crédits K. Brayne

Anjouan – Credits K. Brayne

The four islands of the archipelago of Comoros are the resultant of an intense volcanic activity due to tectonic movements that began nearly eight million years ago. This is very recent on the geological time-scale; by way of comparison, Madagascar, which is a bigger and older island than Comoros, once belonged to the continental landmass between 70 and 120 million years ago.

The islands are roughly distributed according to their age, from east to west, and their age difference is reflected in their current geography. Mayotte (Maoré in Comorian) is the oldest of the four islands and was formed around 7.7 million years ago. Its age means that there has been more time for the elements to erode the rocks, rendering the island relatively flat, covered by a thick layer of soil and disposing of an abundance of fresh water. Well-developed coral reefs circle the island and thus form a lagoon. By contrast, the youngest island Grande Comore (Ngazidja), formed a mere 10,000 years ago, is still being reshaped by an active volcano, Mount Karthala, whose peak reaches some 2361m and has the biggest crater of any volcano in the world. It last erupted in 2007. When you take a tour of the island, you will be able to see the black-rock landscapes which were formed following the most recent lava flow. Due to its young age, the island has a shallow layer of soil which means that rainfall has little chance of seeping into the groundwater and there are no permanent rivers. Only a narrow band of coral reef verges the island.



Pluies - Crédit K. Brayne

Rain – Credits K. Brayne

As for the other two islands, Mohéli (Mwali) is 5 million years old and is formed of a chain of low, central mountains of 790m in height, whileAnjouan (Ndzuani) is younger (3.9 million years) with steep mountain flanks reaching 1595m at the summit of Mount Ntringui. Both of them have permanent rivers.

At a latitude of only 12 degrees south of the equator, the islands enjoy a tropical climate. There are two main seasons. Firstly, the rainy season (Kashkazi) which runs from November to April. The air is warm and humid and the temperatures fluctuate between 28 and 32 degrees Celsius. It is also the cyclone season in the Indian Ocean, although Madagascar often protects the islands from the direct path of cyclones, reducing as a result the impact of violent meteorological conditions in Comoros.  The rains are nevertheless strong, which is why tourism during this season is not recommended. After this, the dry and cool season (Kusi) which runs from May to October, sees temperatures fluctuating between 24 and 27 degrees.