Island areas in Finland

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Finland’s island areas are classified into four categories: the inner archipelago, the intermediate archipelago, the outer archipelago, and archipelagic mainland areas. Areas not included in the island areas are classified as other water and mainland areas. Archipelago exists both in marine and lake areas.

Explore the Categories

Outer Archipelago

The outer archipelago is a type of area consisting of islands in marine waters, located beyond the inner and intermediate archipelago and at a considerable distance from the mainland, without a fixed road connection. The outer archipelago also includes the adjacent continuous water areas surrounding it.

The outer archipelago is characterized by extensive open waters and often long distances between islands. It may also include relatively dense clusters of islands surrounded by large expanses of water. Islands in the outer archipelago can be reached from the mainland and from Åland via archipelago transport services.

Intermediate Archipelago

The intermediate archipelago is a continuous island area located farther from the mainland than the inner archipelago. As a rule, islands account for at least 20% of the area, or the archipelago is connected by archipelago transport services (ferries, cable ferries, or scheduled service vessels). The intermediate archipelago also includes the adjacent continuous water areas surrounding it.

It is typically characterized by a large number of islands and relatively short distances between them. Intermediate archipelago areas commonly occur where archipelagos are extensive and fairly dense, forming a gradual transition from the inner to the outer archipelago. A significant portion of the intermediate archipelago is accessible from the mainland or Åland via archipelago transport services. Fixed road connections to the mainland are very rare.

Inner Archipelago

The inner archipelago is a continuous island area located close to mainland regions (including Åland). In the inner archipelago, land area generally exceeds water area, or the archipelago has a fixed road connection to the mainland. The inner archipelago also includes the adjacent continuous water areas surrounding it.

The inner archipelago is characterized by its proximity to the mainland and the predominance of land area. Most of the inner archipelago is connected by fixed roads and therefore enjoys good accessibility to the mainland. Near the mainland, the inner archipelago may also include areas with a substantial proportion of water surface.

Archipelagic Mainland Areas

Archipelagic mainland areas comprise land areas and their immediately associated water bodies that, in certain respects, resemble archipelago regions. These areas are characterized by the fragmentation of the landscape caused by waterways, resulting in accessibility challenges similar to those found in archipelagos, as well as by the significant presence of water.

Such archipelago-like areas are particularly common in inland lake districts where waterways strongly fragment the landscape, and around large bodies of water where extensive water areas create significant local and regional barriers, for example in relation to nearby population centres.

Island classification

The Island Classification is a statistical and geospatial area classification completed in 2022 that enables the monitoring of development in different types of island areas and archipelagic mainland areas.

The classification is based on a 250-metre statistical grid system that is independent of administrative boundaries. This approach makes it possible to combine other datasets and classifications with island areas, thereby facilitating the monitoring and analysis of development across different types of island areas and archipelagic mainland areas.

The Island Classification was developed by the Finnish Environment Institute (Syke) in cooperation with the Ministry of Agriculture and Forestry of Finland, building in part on earlier methodological and data-development work carried out by Ubigu Oy.