Ngazidja is the largest of the Comoros Archipelago, with an area of 1,147 km2. It is also the most recent island, and therefore has rocky soil. The island's two volcanoes, Karthala (active) and La Grille (dormant), and the lack of good harbours are distinctive characteristics of its terrain. Mwali, with its capital at Fomboni, is the smallest of the four major islands. Ndzuani, whose capital is Mutsamudu, has a distinctive triangular shape caused by three mountain chains – Shisiwani, Nioumakele and Jimilime – emanating from a central peak,  ().