The main area of interest can be divided into four island groups: Stora Nassac.400 closely spaced rocky islets with little or no vegetation. The largest island has maritime Betula forest whilst others support Juniperus. Wet grasslands are also present. Lilla Nassasmaller area than Stora Nassa but with islands more spread out and with very little vegetation. Gillögaflat islands in shallow waters with abundant cover and submerged offshore reefs. Svenska Högarnaa flat island with Juniperus, and heather Calluna. The archipelago is largely uninhabited but during the summer is a popular leisure (boating) area.
This is a very important breeding area for seaducks, waders, gulls and seabirds.
BirdLife International (2019) Important Bird Areas factsheet: Archipelago of Stockholm. Downloaded from http://www.birdlife.org on 21/09/2019.