An archipelago is a group of islands.

Archipelagos are often volcanic, forming along island arcs generated by subduction zones or hotspots, but may also be the result of erosion, deposition, and land elevation. Depending on their geological origin, islands forming archipelagos can be referred to as:

Oceanic islands – mainly of volcanic origin.

Continental fragments – correspond to land masses that have separated from a continental mass due to tectonic displacement.

Continental islands – sets of islands formed close to the coast of a continent are considered continental archipelagos when they form part of the same continental shelf; so islands are just exposed continental shelf in this case.

Indonesia, Japan, the Philippines, New Zealand, Maldives, the British Isles, the Bahamas, Greece, Hawaii, Azores and New York City are examples of well-known archipelagos.

The largest archipelagic state in the world by area and population is Indonesia.

 The archipelago with the most islands is the Swedish East Coast Archipelago.

There is also an Archipelago Sea in Finland.