Bac Mòr
Bac Mòr, also known in English as the Dutchman's Cap, is one of the most dramatically shaped and visually arresting uninhabited islands in the Inner Hebrides of Scotland. Sitting in the Treshnish Isles, a scattered chain of volcanic islands west of the Isle of Mull, Bac Mòr is celebrated above all for its extraordinary silhouette — a broad, flat basaltic platform topped by a steep central cone that rises to roughly 103 metres, creating a profile that is unmistakably reminiscent of an old-fashioned wide-brimmed hat. This distinctive outline is visible for miles across the open sea and serves as a landmark for sailors navigating these waters. It is part of a Site of Special Scientific Interest (SSSI) and a Special Protection Area, protected for both its geological significance and its remarkable wildlife colonies.
The island's name reflects this hat-like appearance. "Bac Mòr" is Scottish Gaelic meaning "large hump" or "large cap," while the popular English nickname, the Dutchman's Cap, was coined by passing mariners who thought its shape resembled the broad-brimmed felt hats worn by Dutch seafarers. The Treshnish Isles as a group have a history intertwined with human settlement and conflict in the Hebrides. While Bac Mòr itself was never substantially settled — its terrain is too inhospitable for sustained habitation — the broader archipelago has been associated with the Lords of the Isles and saw activity during the turbulent clan conflicts of the medieval period. There is a tradition that Hebridean chieftains occasionally used remote islands such as these as refuges.
The geological character of Bac Mòr is what makes it truly exceptional. Like much of the Inner Hebrides, it was formed by Paleogene volcanic activity, and its layered basalt columns and lava flows give the cliffs a dramatic, almost architectural quality. The flat "brim" of the island at sea level is formed from ancient lava platforms, while the central cone is the eroded remnant of what was once a much taller volcanic feature. The rock is dark and weathered, streaked with orange and grey lichens, and the constant crash of Atlantic swells against its cliffsides fills the air with spray and the deep, rhythmic sound of the sea working at the stone. On the summit plateau, the wind is almost always present with considerable force.
The wildlife of Bac Mòr is one of the most compelling reasons visitors make the journey. The island hosts substantial colonies of puffins, razorbills, guillemots, and shags, which nest in the clifftop grasses and rocky ledges in their tens of thousands during the spring and summer months. Grey seals haul out along the rocky shores in significant numbers and are typically unfazed by the approach of a boat. The waters surrounding the Treshnish Isles are rich feeding grounds and regularly attract basking sharks, bottlenose dolphins, and minke whales, making the crossing to Bac Mòr itself a wildlife spectacle. The island's vegetation is limited but includes maritime grasses and sea campion that manage to hold on in the thin soils.
The broader setting of Bac Mòr within the Treshnish Isles places it in extraordinary company. The nearest significant island in the chain is Lunga, to the northeast, which is larger, more regularly visited on wildlife tours, and famous for its puffin colonies. Further northeast lies the Isle of Staffa, home to Fingal's Cave and a UNESCO World Biosphere Reserve candidate site, which is close enough that many boat tours combine both Staffa and the Treshnish Isles in a single day excursion. The Isle of Mull, with its main ferry port at Craignure and the town of Tobermory, is the principal base from which visitors access this entire area.
Visiting Bac Mòr is not straightforward — there is no ferry service and no landing infrastructure on the island itself. Access is exclusively by chartered or tour boat departing from ports including Fionnphort, Ulva Ferry, or Tobermory on Mull. Several established wildlife boat tour operators run seasonal trips to the Treshnish Isles from May through August, when weather and wildlife conditions are at their best. Landing on Bac Mòr itself is rarely part of organised tours due to the difficulty of accessing its steep and rocky shores; most visitors view it from the water, which nonetheless provides spectacular close-up encounters. The island is managed by the Hebridean Trust, which has owned the Treshnish Isles since 2000 and works to protect their wildlife and habitats.
A particularly fascinating detail about Bac Mòr is that its silhouette is so consistent and geometrically unusual that it has served as a reliable navigational reference point in this part of the Hebrides for centuries. Sailors rounding the south end of Mull towards the open Atlantic have used its distinctive cap-shape to orient themselves in conditions of patchy visibility. It appears on historical charts with considerable accuracy, a testament to how memorable and unmistakable its form truly is. For anyone crossing these waters on a clear day, the sight of this dark volcanic hat-shape rising from the silver sea is one of the most memorable views the Scottish coast has to offer.