The Holm Islands


Out in the Bristol Channel are two small and very different islands. Both Steep Holm and Flat Holm serve as a testament to the enduring beauty and resilience of our planet’s wild places

The Bristol Channel is known for its unique geography and rich maritime history. Within this channel lie two remarkable islands that have captivated the imaginations of locals and visitors alike for centuries: Steep Holm and Flat Holm. These islands are small in size but monumental in terms of their natural beauty, ecological significance, and historical importance. Steep Holm and Flat Holm may be geographically close to each other, but they each possess distinct characteristics that set them apart.

Steep Holm: The Rugged Gem

Steep Holm, also known as Steepholm, is the smaller and more rugged of the two islands, measuring only about 48 acres in size. It lies closer to the Welsh coast and is characterised by its steep cliffs, which give the island its name. These cliffs, formed from Carboniferous Limestone, provide a dramatic backdrop to the island’s unique flora and fauna.

Geology and Geography

Steep Holm’s limestone cliffs have been carved by the relentless forces of the Bristol Channel, making it an exceptional geological site. The island also features several sea caves, further adding to its geological appeal. Its cliffs provide important nesting sites for sea birds like gulls and razorbills, making it a paradise for birdwatchers.


The limestone soil of Steep Holm is home to a variety of plant species adapted to its harsh conditions. You can find species like wild leeks, rock samphire, and sheep’s fescue, which have evolved to thrive in this unique environment. The island’s plant life supports a diverse ecosystem of insects and other invertebrates.

One of the most significant aspects of Steep Holm’s ecology is its bird populations. The island is a designated Site of Special Scientific Interest (SSSI) due to the large colonies of sea birds that breed here. Guillemots, kittiwakes, and fulmars find shelter and nesting sites in the island’s cliffs, making it an essential breeding ground for these species. Visitors can observe the sea birds during the breeding season, often flying overhead or perched on the cliffs, providing a memorable wildlife experience.

Human History and Settlement

Steep Holm’s history is as rugged as its cliffs. It has seen periods of human habitation dating back thousands of years. Evidence of prehistoric activity, including flint tools and burial mounds, has been found on the island.

However, it was during the medieval period that Steep Holm saw significant human settlement. A priory was established on the island in the 12th century, and remnants of this monastic community can still be explored today.

During the 19th and early 20th centuries, Steep Holm was used for military purposes. Fortifications were constructed to protect against invasion, and these structures can still be seen by visitors. The island played a role in both World War I and World War II, making it a living testament to the region’s military history.

Today, Steep Holm is managed by the Kenneth Allsop Memorial Trust, a charitable organisation dedicated to preserving the island’s natural and historical heritage. Visitors can take guided tours of the island to learn more about its history, ecology, and conservation efforts.

Flat Holm: The Peaceful Sanctuary

Compared to its rugged neighbour, Flat Holm is aptly named for its relatively flat topography. This island covers an area of approximately 35 acres and is located closer to the English coast. It offers a stark contrast to Steep Holm’s cliffs, providing a peaceful sanctuary for wildlife and a rich history waiting to be discovered.

Geology and Geography

Flat Holm is primarily composed of Carboniferous Limestone, much like Steep Holm. However, the island’s flatter landscape has made it suitable for farming in the past, and evidence of agricultural terracing can still be seen.

Flora and Fauna

Flat Holm boasts a remarkable variety of plant species, including wildflowers like pyramidal orchids, kidney vetch, and yellow rattle. The island’s diverse flora attracts numerous pollinators and other insects.
One of the most notable features of Flat Holm is its substantial rabbit population. These introduced rabbits have thrived on the island, contributing to its unique ecosystem. The rabbits are a key factor in maintaining the grassland, which, in turn, supports various bird species, including breeding populations of lesser black-backed gulls and herring gulls.

Human History and Settlement

The history of Flat Holm is deeply intertwined with its strategic location. Over the centuries, the island has been used for various purposes, including as a quarantine station during the 19th century cholera epidemics and as a defence outpost during times of conflict. The island’s prominent features include a lighthouse, which is still operational, and a series of military buildings, some of which are open to the public as a museum.

One of the most famous historical moments associated with Flat Holm is the 1897 meeting between Marconi and Preece, who carried out some of the earliest experiments in wireless telegraphy on the island. This event marked a significant milestone in the development of modern communication technology.

In recent years, conservation efforts on Flat Holm have been instrumental in preserving and enhancing the island’s natural and cultural heritage. Managed by the Flat Holm Project, the island has been designated as a Local Nature Reserve (LNR) and is open to visitors who can explore its unique history, flora, and fauna.

Conservation and Environmental Significance

Both Steep Holm and Flat Holm are recognised for their environmental importance. They are protected not only for their unique geological and ecological characteristics but also for their significance as breeding grounds for sea birds.

The islands are home to a range of bird species, many of which are threatened in the wider UK context. Guillemots, puffins, razorbills, and kittiwakes all rely on the islands’ cliffs and sea caves as safe breeding sites. These populations play a crucial role in the conservation of these species, particularly as their mainland breeding sites become increasingly threatened by human activities and environmental changes.
In addition to the bird life, the islands also provide a haven for seals. Both common and grey seals can be spotted in the surrounding waters, offering visitors the opportunity to see these marine mammals in their natural habitat.

The islands’ flora, including their unique plant species, contributes to their ecological significance. Preservation of these species is vital for maintaining the islands’ delicate ecosystems and supporting the bird populations that depend on them.

Visiting the Islands

Visiting Steep Holm and Flat Holm is a unique experience for those looking to explore the natural beauty and historical intrigue of these islands. While both islands offer guided tours, there are some important considerations for visitors.

Access to both Steep Holm and Flat Holm is restricted due to their protected status. Visitors can arrange guided tours through the respective organisations that manage each island. These tours provide a unique opportunity to explore the islands’ natural beauty and learn about their history and conservation efforts.

The best time to visit the islands is during the spring and summer months when the weather is milder, and the flora and fauna are at their most active. However, it’s essential to check with the island authorities for tour availability and any seasonal restrictions.