Natural environment

Suomenlinna is a cultural environment where human contributions to the landscape and the original natural environment of the archipelago merge in a unique blend. The fortress was built on a cluster of rocky skerries known as Susiluodot, which back then were virtually treeless; today, Suomenlinna has far greater biodiversity.

The lime leached from the old buildings has made the rocky soil fertile and thus capable of supporting a variety of plant and animal species. There are both man-made and natural green areas in the landscape: parks, gardens, vegetable patches, shores and meadows in their natural state, and earthworks. Rocky shores and fortress walls encircle the islands.

Seasons

Weather and the changing seasons affect the landscape dramatically on Suomenlinna. Because of the proximity of the sea, the air is humid and windy. However, not much rain falls in the summer; showers on the mainland often do not reach the islands. The sea strengthens the impact of sunshine. The flora and fauna are at their richest in summer, but Suomenlinna is full of life at all times.

Spring arrives about a week later than on the mainland. Autumn, on the other hand, is long and warm. In spring and autumn, innumerable migratory birds fly over the islands. Winter is a quieter time, as nature lies dormant. Some birds stay on the islands over the winter, feeding on remaining plants and at residents’ bird feeders. The humid maritime climate may thaw the snow quickly, but on the other hand snow tends to stay on the ground more readily on Suomenlinna than on the mainland, because there is virtually no vehicle traffic on the islands.

Water areas

More than half of the area within the perimeter of Suomenlinna, 80 hectares, is water. Of special interest in the water areas are the historical underwater relics studied by the Maritime Archaeology Unit of the National Board of Antiquities. An inventory of underwater sites was begun in 2007. Side scan sonar technology produces images of the sea bed equivalent to aerial photography. Any underwater finds are inspected in situ by divers. The underwater cultural heritage of Suomenlinna is related to the military history of the fortress. The area contains, depending on how it is delimited, 22 to 44 wrecks of various ages, 18 submerged structures and 13 individual underwater relics.

For example, the underwater obstacle to the northwest of Länsi-Mustasaari island is a relic of national importance. This is a defence structure consisting of log-built coffer dams and ships scuttled between them. It dates from the 19th century.

Visitors

A great many Finnish and foreign visitors come to Suomenlinna every year. The popularity of the fortress is a mixed blessing, since the hundreds of thousands of visitors promote erosion of the soil, which in turn threatens the biodiversity of the islands. The sensitive natural environment can best be protected by keeping to established routes and by letting all plants grow where they stand. Further instructions can be found in the Regulations.