Archipelago Ertholmene: Charming Islands Concealing History and Nature

Ertholmene, also known as Christiansø, is a unique place of immense charm and rich history. Located 18 km northeast of Bornholm, these picturesque islands constitute the easternmost point of Denmark. Although Ertholmene covers only 39 hectares, it continues to attract the attention of many visitors who seek to explore this unique enclave.

The archipelago consists of three main islands: Christiansø, Frederiksø, and Græsholm. Christiansø, named after King Christian V, occupies an area of 22.3 hectares. It is here that one can uncover the history of a fishing settlement surrounded by impressive fortifications that protected these lands from the perils of the sea. Frederiksø, covering an area of 4 hectares, is a place where one can immerse themselves in tranquility and enjoy the charm of nature. On the other hand, Græsholm, spanning 11 hectares, is a bird reserve where various species can be encountered, allowing visitors to observe their lives in their natural habitat.

Ertholmene is an area that lacks legal personality and does not belong to any municipality or region. Managed by the Danish Ministry of Defense, the islands are state-owned. Despite being home to a small community, their cultural, historical, and natural significance is immense.

Fishing and tourism are the main sources of income for Ertholmene. Approximately 80,000 tourists, mostly on day trips from nearby Bornholm, visit the islands annually. Visitors have the opportunity to immerse themselves in the islands' history, stroll through charming streets, admire breathtaking sea views, and savor fresh seafood, which is characteristic of the area.

Ertholmene is also a popular destination for sailors and yacht enthusiasts. The pristine waters, picturesque landscapes, and favorable navigational conditions attract sailing enthusiasts who seek unique adventures at sea.

Diving on Bornholm

Discover the fascinating history of the Ertholmene Islands, which have played an important role in Danish maritime history for centuries and have preserved their picturesque character to this day

The Ertholmene archipelago has a rich and interesting history dating back to the Middle Ages. Since that time, fishermen from the nearby island of Bornholm have used these islands as temporary shelters. However, it was the Danish-Swedish conflicts in the late 17th and early 18th centuries that brought the first permanent residents to Ertholmene.

Denmark, needing a strategic naval base in the central part of the Baltic Sea, decided to build a fortress on the islands of Christiansø and Frederiksø in 1684. This fortress served as an important outpost for the Danish Navy until 1855. The church on Christiansø, initially serving the garrison, bears witness to this military heritage.

The population of the islands reached its peak in 1810 when a census showed 829 inhabitants. These were soldiers who resided on the islands due to the wars of the gunners. The historical buildings, once serving military purposes, now serve as residential spaces for the local community, and some of them are rented to tourists during the summer. Ertholmene has preserved its unique external appearance for over 300 years. With its thick granite walls surrounding it, adorned with old cannons aimed towards the sea, Christiansø presents itself as a picturesque place that seems frozen in time.

A part of the former fortress, known as Store Tårn, has been serving as the Christiansø lighthouse for over 200 years. Meanwhile, the small round tower on Frederiksø, known as Lille Tårn, has been transformed into a museum that houses numerous artifacts and stories related to the islands.

Diving on Bornholm

Discovering the Charm of the Ertholmene Archipelago: Painters, Nature, and the Unique Character of the Islands

Ertholmene, though small and picturesque, possesses an extraordinary allure. It was the artists, particularly painters, who played a key role in uncovering the beauty of these islands. Enchanted by their rugged landscapes and distinctive atmosphere, they began to settle there, and to this day, a small group of artists resides permanently on the islands. In their eyes, Ertholmene has become a source of inspiration and a place where they can create in harmony with the surrounding beauty.
However, the artists' discovery of the islands is just the beginning. As part of a nature reserve, Ertholmene is also a paradise for flora and fauna enthusiasts. Here, one can encounter unique species of plants and animals that are found nowhere else. It is a place where nature has preserved its authenticity and unspoiled character.
While strolling through the islands, one can admire not only the beauty of nature but also the picturesque local architecture. The islands have retained many historical buildings, and the remnants of former fortifications serve as reminders of the archipelago's rich past. Importantly, any interference with the existing state of the islands is strictly prohibited. As a result, Ertholmene continues to emanate the atmosphere of centuries past, and even television antennas are hidden inside buildings to preserve the authenticity of the landscape.

Diving on Bornholm


Graesholmen, an uninhabited island in the Ertholmene Archipelago, has its unique history and role in nature conservation.

Unlike the inhabited islands of Christiansø and Frederiksø, Graesholmen was never populated. During the construction of the fortress in 1684, when the plague spread among the working men, the deceased were buried in the Plague Cemetery on Graesholmen. This tragic event left its mark on the island's history.

Today, Graesholmen is an ornithological reserve, serving as an important habitat for birds. It is the only place in Denmark where guillemots and razorbills have their breeding grounds. In the bird reserve known as Greensholm, approximately 10,000 pairs of silver gulls and guillemots have found their home. During spring and autumn, millions of small birds migrate across the Baltic Sea to their northern breeding areas, and large numbers of migratory birds seek food and rest on Christiansø before continuing their journey.

Unfortunately, Graesholmen is closed to visitors to protect its unique fauna and flora. This decision ensures peace and safety for the birds that nest there and play a significant role in the ecosystem of the Ertholmene Archipelago.

Graesholmen, though inhospitable to humans, serves as an oasis for wildlife and is evidence of how the islands of the Ertholmene Archipelago play an important role in the preservation and conservation of unique ecosystems.

tovbanen on Bornholm
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