Complex sentence: Flinders Island is only one of the many islands included in the Municipal area, although Flinders Island itself is the only island with more than one permanent settlement and is by far the largest in the Furneaux Group.
Split into simpler sentences: Flinders Island is only one of the many islands included in the Municipal area. Of these islands Flinders Island is the only island with more than one permanent settlement, and is by far the largest in the Furneaux Group.