Koster usually means the two main islands, Nordkoster and Sydkoster. The islands are almost car-free and surrounded by Kosterhavet, Sweden’s only marine national park. You can explore on foot or by bicycle; the islands have marked walking routes.

Nordkoster has two circular routes, each just under 5 kilometres. The route takes in the cobble fields, where rounded stones cover the ground, and the lighthouse viewpoints at Högen, the island’s highest point. On Sydkoster, a walk around the island is about 14 kilometres. Shorter sections of 3 to 7 kilometres are also possible.

Sydkoster’s listed sights include the Kosterhavet visitor centre, the viewpoint at Valfjäll, Breviks harbour, Kilesand beach and the snorkel trail at Rörvik. The island can also be explored by bicycle. Kosters Trädgårdar has a restaurant, café and farm shop. Pensionat Ekenäs Koster and Kostergården offer food and accommodation. A walking and cycling map is available to download.