Walk on Ailsa Craig. Rising like a colossal volcanic plug from the Firth of Clyde, Ailsa Craig is one of Scotland’s most iconic and enigmatic islands. Often called Paddy’s Milestone for its halfway mark between Belfast and Glasgow, this remote granite outcrop offers an unforgettable walk through time, nature, and geology.
Getting There
Reaching Ailsa Craig is part of the adventure. Boat trips leave from Girvan harbour, weather permitting, and the journey west across the sea sets the tone — a slow reveal of the towering 340-metre rock that dominates the horizon. Once ashore at the island’s small jetty, you’re stepping onto a place where nature and history collide.
Walk on Ailsa Craig – The Walk Itself
There are no formal trails or paths on Ailsa Craig, but walkers can make a rewarding circuit (around 2.5 miles) by following the old quarry tramways, climbing towards the ruins of Ailsa Castle, and, for the adventurous, ascending higher slopes to the Garry Loch — a remote freshwater lochan perched at over 240 metres above sea level. The walk is steep, rugged, and unmarked, with no facilities, so sturdy boots and navigation skills are essential.
Highlights include:
- The Lighthouse: Built by Thomas Stevenson in the 1880s, it marks the eastern shore. Though now automated, its story is deeply tied to the island’s maritime history.
- Castle Ruins: A 16th-century Hamilton fortress with crumbling walls and a windswept view across the sea.
- Tramway and Gasworks: Rusting rails and weathered machinery hint at the days when granite from the island was quarried for curling stones.
- South Foghorn and Stone Crusher Ruins: Atmospheric remnants of industry clinging to the cliff edge.
Wildlife & Nature
Ailsa Craig is now a protected bird sanctuary leased by the RSPB until 2050. Huge colonies of gannets, guillemots, razorbills, and, more recently, puffins call the cliffs home. The eradication of rats in 1991 allowed puffins to return and breed successfully. You’ll hear the wild cries of seabirds echoing across the rocks, and with luck, spot slowworms sunning themselves near the pathless upper slopes.
Gannetry: A Towering Colony of Northern Gannets
Ailsa Craig is home to a nationally significant gannetry, hosting over 36,000 pairs of Northern Gannets (Morus bassanus), making it one of the largest breeding colonies in the world. These elegant, white-plumaged seabirds are famous for their six-foot wingspans and dramatic plunge-diving skills.
Why Ailsa Craig? The island’s steep, isolated cliffs are ideal for gannet nesting. These birds prefer sheer, inaccessible ledges where they’re safe from ground predators and have easy take-off access for foraging trips. The vast availability of open sea around Ailsa provides a rich hunting ground for mackerel, herring, and other fish.The entire upper reaches of the island’s cliffs on the west and north faces are blanketed white in summer — not just from the gannets’ plumage, but also the guano (bird droppings) that coats the rocks. The colony creates a raucous, pungent, and unforgettable atmosphere of constant motion and noise.
Nesting & Breeding – Gannets return to the colony each spring (typically April–August), where they:
- Lay a single bluish egg, incubated by both parents using their large, webbed feet.
- Build nests from seaweed, grasses, and sadly, sometimes marine plastic.
- Fledge chicks after around 13 weeks, which then leap off the cliffs and glide out to sea.
Young gannets may spend several years at sea before returning to breed — often at their birth colony.
Protection & Conservation
The Ailsa Craig gannetry is protected as part of the island’s status as a Special Protection Area (SPA) and is leased to the RSPB until 2050. The eradication of invasive rats in 1991 was crucial for the recovery of seabird populations, including puffins and gannets, which now thrive undisturbed.
Geology & Curling Stones
This island is made of microgranite, an extremely hard rock prized for making curling stones. In fact, most of the world’s curling stones come from here. Look out for polished boulders and signs of quarrying near Kennedy’s Nags, the island’s granite extraction site.
Echoes of the Past
From religious refugees in the 1500s to smuggling caves and pirate stories, Ailsa Craig has a rich, hidden history. There are tales of chapels on the summit (likely mythical), smugglers’ graves in caves, and even a Victorian tea room with white tablecloths and fresh scones — once run by Margaret Girvan for passing fishermen and lighthouse workers.
Curious History & Human Folly
Ailsa Craig has always drawn characters as bold as the rock itself — from religious refugees and pirates to smugglers and marquesses with curious ideas.
Smuggling tales are woven deep into the island’s lore. The MacNall Cave, tucked high above the southern shore, is named after a supposed 18th-century smuggler. When the cave was later cleared of guano, two stone coffins containing human bones were discovered — perhaps final resting places for MacNall and a comrade, or simply victims of Ailsa’s treacherous past. The island’s caves and hidden coves would have made ideal hideouts for contraband bound for the Ayrshire coast.
In more recent history, Ailsa Craig became the private domain of the Marquess of Ailsa, who held title over the island for centuries. One such owner, embracing the eccentricity that often comes with remote island ownership, introduced a strange cast of mammals to the island — including badgers and even raccoons. While the badgers didn’t survive long, the raccoons bred successfully for several years. Their presence devastated the local slowworm population before they, too, vanished. It’s one of those stories that seems too strange to be true — but on Ailsa Craig, the line between myth and memory is wonderfully blurred.
Puffins Return Thanks to Rat Eradication
Not all of Ailsa Craig’s invaders were introduced on purpose. For decades, the island’s vast seabird colonies were devastated by rats, most likely brought ashore via 19th-century shipwrecks, including a sunken coal boat. The biggest victims? The puffins, whose burrow nests were easy pickings for hungry rodents.
But in 1991, a pioneering rat eradication project began. It was one of the first of its kind in the UK — remote, rugged, and risky. It succeeded.
Since then, puffins have slowly returned, raising chicks once more on the slopes of this wild granite rock. Their colourful bills now brighten Ailsa Craig’s ledges each summer, a hopeful symbol of how nature can recover when given the chance.
Tips for Visiting
- No shelter or facilities: Bring everything you need, including food, water, and waterproofs.
- Uninhabited and rugged: There’s no path, so be prepared for uneven, overgrown terrain and steep climbs.
- Respect wildlife: It’s a sanctuary first and foremost, especially during breeding season (spring–summer).
- Weather is key: Landings are only possible in calm conditions. Always check with tour operators.
Ailsa Craig is not a place of comfort or convenience — it’s a raw, elemental journey into Scotland’s geological and cultural past. But for those who venture there, it’s an unforgettable wild walk across one of Britain’s most remarkable sea stacks. Why not take a Walk on Ailsa Craig?