The Comoro Islands are a chain of four volcanic islands lying at the northern end of the Mozambique Channel between the tip of Madagascar and the East African coast. The BCSF Project works in three of the islands. Grande Comore is the youngest and largest island, dominated by Mount Karthala, which has the largest crater of any active volcano in the world; Mohéli is a small tropical paradise with beautiful beaches and reefs; and Anjouan, where the BCSF Project is based, is notable for its steep mountain slopes and ravines.
Since they emerged out of the sea, the islands have never been joined to any other landmass. This isolation meant that animals and plants which arrived on the islands by air or sea were then cut off from the rest of their kind, and many evolved independently into new species unique to the Comoros (endemic species).