Complex sentence: The Mafia island cluster consists of one large island (394km²) and many off-shore islands around it--inhabited as well as uninhabited, including Chole Island (2km²) with a population of 800.
Split into simpler sentences: The Mafia island cluster consists of one large island (394km²) and numerous smaller ones. Some of these are inhabited, such as Chole Island (2km²), with a population of 800.