[2] Ertholmene are situated 18 kilometres (11 mi) northeast of Gudhjem, Bornholm, and include Denmark's easternmost point.

[4] Today the economy of Ertholmene is almost entirely based on tourism, with tens of thousands of visitors each year, the majority on day-trips from Bornholm during the summer months.

[4] The archipelago's buildings and nature are protected by law, and access to the uninhabited islands is restricted.

[5] Ertholmene consists of three main islands, Christiansø, Frederiksø and Græsholm, plus a number of rocks and skerries.

As Denmark needed a naval base in the central Baltic Sea, a fortress was built on Christiansø and Frederiksø in 1684 which served as an outpost for the Danish Navy until 1855.

Girdled by thick granite walls with old cannons pointed seaward, Christiansø is a picturesque tourist spot seemingly frozen in time.

Instead they are state property governed by an administrator, appointed by the Danish Ministry of Defence, with the responsibility being the tasks normally performed by municipalities and other public sector civil services.