A sea stack is an isolated pillar of rock near a coast, usually left behind as waves exploit cracks in a headland. Caves can enlarge into arches; when an arch roof collapses, a stack remains offshore. The sequence is a useful model, not a timetable: rock type, joints, storms, currents, and local geology produce different shapes and rates of change. These ten examples are snapshots in landscapes that are still evolving.
1. Twelve Apostles, Australia
Victoria’s famous limestone stacks rise beside the high-energy Southern Ocean. Despite the name, there were never twelve standing together. Parks Victoria explains that caves and arches formed as the coast retreated, leaving pillars that continue to erode. One stack collapsed dramatically in 2005, demonstrating that permanence is an illusion here.
2. Old Man of Hoy, Scotland
This tall sandstone stack stands off Hoy in Orkney. Its form reflects erosion along weaknesses in layered rock. It is also a celebrated climbing objective, but exposed conditions and nesting wildlife make it a place for experienced climbers operating within local guidance, not casual scrambling.
3. Dún Briste, Ireland
At Downpatrick Head in County Mayo, Dún Briste is a flat-topped stack cut off from the mainland. Horizontal rock layers make its structure especially visible. Local tradition gives the formation cultural meaning, while geology records repeated marine erosion along Ireland’s Atlantic edge.
4. Reynisdrangar, Iceland
Dark basalt stacks stand offshore from Reynisfjara on Iceland’s south coast. Folklore describes petrified trolls, while the rocks themselves belong to a volcanic landscape reshaped by the sea. The beach is also known for dangerous sneaker waves. Visitors should obey closures and remain far from the water, even in apparently calm conditions.
5. Ball’s Pyramid, Australia
Ball’s Pyramid is a steep volcanic remnant southeast of Lord Howe Island. Rather than a typical fragment of a retreating sedimentary cliff, it is the exposed residue of an ancient volcanic system. Its isolation supports unusual ecology, including the conservation story of the Lord Howe Island stick insect.
6. Kicker Rock, Ecuador
Known locally as León Dormido, this eroded volcanic formation rises from waters near San Cristóbal in the Galápagos. A channel divides its main masses. The setting is biologically sensitive, so access and wildlife encounters should follow Galápagos National Park rules and authorized-tour guidance.
7. Lange Anna, Germany
This red sandstone pillar stands near Heligoland in the North Sea. Waves, salt, weather, and fractures continue to weaken it. Viewing from designated paths is safer than approaching unstable cliff edges, and it reduces trampling in a small, heavily visited coastal environment.
8. Risin og Kellingin, Faroe Islands
The “Giant and the Witch” are two stacks off Eysturoy. Their names come from a Faroese legend, an example of how communities turn conspicuous landforms into memorable stories. The rock towers are best understood from safe shore viewpoints rather than as fixed objects guaranteed to endure.
9. Haystack Rock, Oregon
Haystack Rock at Cannon Beach is part of the Oregon Islands National Wildlife Refuge. Its intertidal pools and seabird habitat are as important as its outline. Seasonal protections, leash rules, and tide awareness help visitors avoid disturbing nesting birds or becoming trapped by incoming water.
10. Branaunmore, Ireland
Standing below the Cliffs of Moher, Branaunmore was once connected to the cliff line. The site’s alternating sandstone, siltstone, and shale layers respond differently to erosion. Official guidance emphasizes staying on marked paths because the cliffs are active and collapses can occur without warning.
Viewing a changing coast responsibly
- Use official overlooks and check tides, wind, and local closures.
- Never stand beneath an unstable cliff or cross barriers for a photograph.
- Keep distance from nesting birds and marine mammals.
- Do not climb stacks unless access is legal and you have the required expertise.
Sea stacks inspire wonder because they make deep time visible. Their fragility is not a flaw; it is the central fact of the landscape.
Sources: Parks Victoria; UNESCO: Lord Howe Island Group; U.S. Fish and Wildlife Service; Cliffs of Moher official geology guide.
