🇮🇪 Ireland · West and North
The Giant's Causeway is the most astonishing landscape in Northern Ireland and one of the great geological wonders of the planet: some 40,000 basalt columns, almost all hexagonal, fitted together like a giant honeycomb that steps down into the sea. Walking on those perfect stone treads, with the Atlantic breaking at your feet and black cliffs behind, is one of those experiences you remember for life. No surprise that Unesco declared it a World Heritage Site in 1986.
Its origin has two versions, and both are worth telling. Science explains that the columns formed around 60 million years ago, when an enormous lava flow cooled slowly and contracted, fracturing into those regular prisms. Legend, on the other hand, says the causeway was built by the Irish giant Fionn mac Cumhaill (Finn McCool) to cross the sea and take on a Scottish giant. In these pages we tell you which is which, without taking the magic out of either.
This guide gives you all the practical detail and one key fact that saves an expensive mistake: walking to the stones is FREE (it is a public path); what you pay for is the visitor centre and its car park. You will also find how to get there from Belfast, what to see along the coast (Carrick-a-Rede, Dunluce, the Dark Hedges), and why you pay in pounds here and not in euros, even though you crossed from the Republic without any border check.
The Giant's Causeway has a double history, the geological and the legendary. The real one: some 60 million years ago, at the start of the Palaeogene, the opening of the North Atlantic Ocean caused intense volcanic activity (the North Atlantic Igneous Province); a flow of basaltic lava cooled and contracted, forming the famous hexagonal columns. The legendary one: the giant Fionn mac Cumhaill is said to have raised the causeway to cross to Scotland and fight the giant Benandonner, hence the formations on both sides of the sea. For science, the site was 'discovered' for the world in 1693, when it was presented to the Royal Society, and in the eighteenth and nineteenth centuries it was the setting for a celebrated dispute between 'Neptunists' (who attributed the rocks to a primeval ocean) and 'Plutonists' (who explained them by volcanic fire), which modern geology would settle in favour of the latter. Victorian tourism made it fashionable, with a pioneering electric tramway opened in 1883, and Unesco confirmed it as a World Heritage Site in 1986. The full story is on our history page.
Read the full history ↓The Atlantic west and the north: Galway and its Fourteen Tribes, the Connemara of the famine roads and Kylemore, the Aran Islands as a refuge of the Irish language, the Cliffs of Moher above the karst of the Burren, and the Giant's Causeway, in Northern Ireland (United Kingdom), with its geology and the plantation of Ulster.
Read the history of West and North →No exact prices: a scale from $ (budget) to $$$$$ (luxury), with 2-3 options per category.
Origins, formation and what the sources say.
The true story of the Giant's Causeway begins some 60 million years ago, at the start of the Palaeogene period, in a world without humans and in the middle of geological upheaval. At that time the ancient supercontinent of Laurasia was breaking up and the North Atlantic Ocean was beginning to open. Along that gigantic crack in the Earth's crust, colossal volcanic activity broke out, which geologists group under the North Atlantic Igneous Province, and which left its mark in northeast Ireland as well as in Scotland, the Faroe Islands, Iceland and Greenland.
In what is now County Antrim, successive flows of very fluid basaltic lava spilled across the landscape and formed a thick basalt plateau. The key to the famous columns lies in how one of those flows cooled: cooling slowly and uniformly, the basalt contracted, and that contraction generated internal stresses that fractured the rock into a regular pattern of vertical cracks. The most efficient geometry for releasing that stress tends towards the hexagon, which is why most of the roughly 40,000 columns of the Causeway have six sides, though there are four-, five-, seven- and even eight-sided ones. It is the same phenomenon, on a monumental scale, that cracks dried mud or a layer of starch as it dehydrates.
The result is one of the most perfect and most studied examples of columnar jointing on the planet: a blanket of stone prisms stepping down into the sea. Recent research has even pinned down the temperature at which the key fracturing took place (around 840-890 °C), refining our knowledge of a process that science, in essence, already understands well: there were no giants here, just lava, time and physics.
Against the scientific explanation, popular tradition has its own, far more colourful version, and it is worth being clear that it is folklore, not history. According to legend, the Causeway was built by the Irish giant Fionn mac Cumhaill (anglicised as Finn McCool), hero of the Fenian Cycle of Irish mythology and leader of the Fianna, the band of warriors who roamed Ireland in the golden age of myth.
The story goes that Fionn fell out with a Scottish giant called Benandonner, who was challenging him from across the sea. To go and fight him, Fionn tore chunks from the Antrim coast and drove them into the sea bed, building a stone causeway that joined Ireland with Scotland (which would also explain why, on the other side of the channel, on the Scottish island of Staffa, in Fingal's Cave, there are identical basalt columns: they are, in fact, part of the same geological formation).
The ending is a joke about cunning: on seeing at close quarters how enormous Benandonner was, Fionn took fright and ran home. His wife Oonagh had the idea of dressing him as a baby and putting him in a cradle. When Benandonner crossed the causeway and saw the size of the supposed 'baby', he assumed the father must be a colossal giant, was terrified and fled back to Scotland, tearing up the causeway behind him so Fionn could not follow. That, says the legend, is why the Causeway breaks off in the sea. It is a charming tale that gives the place its name, but the stone was laid by volcanism, not by a giant.
Although the people of Antrim had always known the Causeway, for the world of European science the site 'appeared' at the end of the seventeenth century. In 1693 a paper on the formation was presented to the Royal Society in London, attributed to Sir Richard Bulkeley of Trinity College Dublin, although the person who had actually visited and described it shortly before was the bishop of Derry. From then on, the Causeway began to attract naturalists, artists and the curious, and some famous eighteenth-century illustrations made it known across Europe.
And then the Causeway became, without meaning to, a battlefield in one of the great disputes in the history of geology: the one that pitted 'Neptunists' against 'Plutonists' in the late eighteenth and early nineteenth centuries. The Neptunists, who followed the ideas of the German Abraham Gottlob Werner, held that all rocks, including basalt, had crystallised out of the waters of a primeval ocean that once covered the Earth. The Plutonists, following the Scot James Hutton, argued instead that rocks such as basalt had an igneous origin, that is, that they came from the cooling of molten material from the hot interior of the Earth.
The basalt of the Giant's Causeway was key evidence in that debate: had it 'precipitated' out of the sea or 'solidified' out of fire? The dispute was long and bitter, with implications reaching beyond geology, touching even the biblical chronology of the world. In time the evidence prevailed: the volcanic origin of basalt — the Plutonist position — turned out to be correct, and the Causeway remained a monument not only to nature but also to the history of how science learned to read rocks.
The nineteenth century turned the Giant's Causeway into one of Ireland's first great mass tourist attractions. The Romantic fashion for the sublime and the picturesque, scientific interest and better transport drew crowds of Victorian visitors eager to see the wonder in stone. Local guides appeared — at times excessively insistent — along with souvenir stalls and a whole small economy around the phenomenon; so much so that in 1961 the National Trust took over its management precisely to bring order and protect the place from commercial excess.
The most notable landmark of that era was technological. In 1883 the Giant's Causeway Tram opened, a tramway linking the seaside resort of Portrush with Bushmills and the Causeway along some 15 kilometres. It was no ordinary tram: it was hailed on opening as 'the world's first long-distance electric tramway' and, more remarkably still, it was the world's first tram system powered by hydroelectricity, generated at a station on the river Bush. A display of Victorian modernity in the service of tourism, in the depths of rural Ireland.
The opening ceremony with electric traction took place on 28 September 1883, although full regular service began somewhat later and for years ran alongside steam locomotives. The tram operated until 1949 and is now remembered as a pioneering curiosity; along part of its old route, since 2002, a narrow-gauge heritage railway has run, the Giant's Causeway and Bushmills Railway, reviving the spirit of that golden age of tourism on the coast.
In 1986, the Giant's Causeway and Causeway Coast were declared a Unesco World Heritage Site, the first site in Northern Ireland to receive that distinction. The recognition rested both on the exceptional geological value of the place — a world example of columnar jointing and an archive of Palaeogene volcanic activity — and on its importance in the history of the earth sciences. More recently, it has also been included among the first geological heritage sites recognised internationally by the world geological community.
The protected area covers not only the most famous columns but several kilometres of cliffs and bays along the Antrim coast, with their succession of lava flows, reddish soils between the basalts (the 'interbasaltic beds') and spectacular formations. Management, in the hands of the National Trust, seeks to balance the conservation of a fragile heritage with enormous tourist pressure: the Causeway receives hundreds of thousands of visitors a year and is the most visited natural attraction in Northern Ireland, which means channelling the flow of people, protecting the columns from wear and educating people about their value.
One important and sometimes misunderstood feature is access: thanks to a public right of way confirmed by a court in 1897, anyone can walk to the stones free of charge at any hour; what you pay for is the visitor centre experience and its car park. Situated in Northern Ireland — part of the United Kingdom — the Causeway is visited by crossing from the Republic a border that today has no checks, the result of the 1998 Good Friday Agreement that sealed the peace after decades of conflict; but the traveller notices the change in details such as the currency (here, pounds sterling) and the signage. Between science and myth, between ancient lava and recent history, the Giant's Causeway remains one of the most fascinating places in all of Ireland.