Types of archipelagos
Archipelagos are usually found in the open sea; less commonly, a large land mass may neighbour them, an example being Scotland which has more than 700 islands surrounding the mainland. Archipelagoes are often volcanic, forming along mid-ocean ridges or hotspots, but there are many other processes involved in their construction, including erosion, deposition, and land elevation.
The four largest modern states that are mainly archipelagos are Japan, the Philippines, the United Kingdom and Indonesia (the world's largest archipelagic state according to the CIA World Factbook).
The largest archipelago in the world by size is the Canadian Arctic Archipelago of Northern Canada. It is situated in the Arctic Ocean.