Complex sentence: São Miguel Island (named for the Archangel Michael or, literally, Portuguese for Saint Michael), is also referred to locally as "The Green Island", is the largest and most populous island in the Portuguese archipelago of the Azores.
Split into simpler sentences: São Miguel Island (named for the Archangel Michael or, literally, Portuguese for Saint Michael), has been nicknamed "The Green Island". It is the largest and most populous island in the Portuguese archipelago of the Azores.