An archipelago is a group of islands often formed by volcanic activity. Examples can be found in the open ocean, as well as near large tracts of land. The former is generally more common than the latter.
The Galapagos Islands are an example of an archipelago.
In some cases, an archipelago forms because it is over a hot spot in the ocean. There are about 50 identified hotspots that are defined as having a prolonged period of active volcanism. One famous group is the Hawaiian Islands, which sit on top of an ocean hotspot.
Erosion and sediment deposits can influence how an archipelago forms. For example, when islands are close to a larger land mass, they may have previously been connected to that land mass. Both erosion and shifting of tectonic plates may have resulted in parts of the landmass drifting apart or drifting apart. This is usually a very time consuming process.
If volcanic activity remains reasonably constant, the deposition of volcanic materials can actually expand an island.
Due to volcanic activity, the islands of an archipelago can reduce or increase in size. If volcanic activity remains reasonably constant, the deposition of volcanic materials can actually expand an island. Since the island is surrounded by water, it is also subject to relatively continuous erosion. Intense volcanic activity can also completely decimate an island in an archipelago. The weather can certainly have an effect on the islands as well. Those located in tropical regions are subject to violent hurricanes.
The Aegean Sea is known as an archipelago due to the many islands that dot its surface, including the stunning Santorini.
There are many archipelagos in the world and the definition can refer not only to a group of islands, but also to any sea that has several small islands. The Aegean Sea is considered an archipelago due to its many land masses. An island group does not necessarily have to be small, nor does it have to always be unstable. The British Isles, for example, are a large and stable group, and the Florida Keys include at least 1,700 small islands that stretch from the southern tip of Florida. Another large archipelago are the islands that make up New Zealand and New Guinea.