A large area of both inner and outer archipelago situated off Porkkala peninsula in the central part of the Gulf of Finland. The archipelago is dominated by large areas of open water. Most of the islands are small, barren and rocky, but a few are larger and forested. Some islands have small areas of low vegetated shore meadows and shallow lagoons. The main human activity is recreational boating but landing is forbidden on many islands. Few islands have cottages or other buildings.
Nationally important populations of Larus marinus (67-70 pairs) and Larus argentatus (1,865 pairs) also breed. Species of global conservation concern that do not meet IBA criteria: Polysticta stelleri (up to 40 birds on passage, irregular), Haliaeetus albicilla (3 individuals, passage).
Pressure/threats to key biodiversity
There has been a bird observatory on Rönnskär island for many years, carrying out bird ringing and observing migration. The area is a candidate SAC.
National Low International None171 ha of IBA covered by Protected Area on Private Lands (Brändt, 9 ha; Gadd, 15 ha; Sommaröarna, 13 ha; Galjonsgrund, 76 ha; Salmen, 19 ha; Enbusken-Rönnbusken, 41 ha). 506 ha of IBA covered by Specific Protection Area (Porkkalan Saaristo, 372 ha, Kanskogbroken-Bergstadbrotten, 134 ha).