Vanuatu is an archipelago composed of approximately 82 small islands.
Vanuatu is an archipelago composing approximately 82 small islands.
Vanuatu is an archipelago composed of approximately 82 small islands.
Vanuatu is an archipelago composing approximately 82 small islands.
The verb "compose" relates parts to whole. If the whole is the subject, the verb must be passive: "[whole] is composed of [parts]." Here, an archipelago is the "whole", and the islands are the "parts."