Answer:
A group or a chain of islands is called archipelago.
Explanation:
The seas and oceans are not just open spaces of water with nothing interrupting them, instead they have hundreds of thousands or even millions of islands rising from them. The islands vary in size, and what can be considered as an island is still debatable, but they can be anywhere from few tens of meters to hunderds of thousands of square km.
The chains or groups of islands are called archipelago. In order to distinguish them from one another they have to have some similraties and most often they need to have the same geological history and processes that created them. An archipelago can be formed in multiple ways. Along the subduction zones there are always archipelagoes, and this is due to the volcanic activity. Another creator of archipelagoes are the hot spots because they are static but the plates move on top of them, thus draging the islands from the hot spot and new rising above it. Also, if the characteristics of the topography of an area are such that when the sea levels rise, there can be a formation of an archipelago where the lower areas will be under water while the higher places would remain above water.
