Inishcoo's interior is mainly rocky, formed of the granite that underlies much of the western Donegal coast. A small lake sits among the outcrops. The granite is the same stone that makes Errigal pink and the Bloody Foreland red at certain angles of sunset, the same rock that was quarried for so much of Donegal's stone buildings. On a small island, the geology determines everything: where you can grow anything, where you can put a house, where the wells will be. Inishcoo has very little soil and almost no shelter. What buildings exist hug the shoreline. The 1901 and 1911 censuses still recorded permanent residents on Inishcoo, in the townland of Templecrone parish. By the mid-twentieth century, that pattern had begun to end. The island was no longer a place to live a working life from.

The largest building on the island, in the south-western corner, was a coast-guard station. The Rosses coast in the nineteenth century needed watching: smugglers ran goods in and out of these channels, distressed ships went onto the rocks, the relationship between the British state and the local population was perpetually strained. Coast-guard stations were placed on small islands and headlands across the Atlantic coast. After Irish independence, most of them were decommissioned. Some became private homes. The Inishcoo station has been converted into a holiday house, a sturdy stone building now repurposed for a use its builders never imagined. The Wikipedia entry notes its existence laconically. The story of how it was used and by whom and what its closure meant for the island is mostly unwritten.

Several of the old houses on Inishcoo are now used as holiday homes. Others, like the one photographed for the Wikipedia article from the deck of the Arranmore ferry, are derelict, with rotting roofs and weather-beaten walls. The juxtaposition is common across the Donegal islands: a few well-maintained holiday cottages, some lived in occasionally, others standing empty, and the ghosts of homes that the families who once owned them never sold or never returned to. The island has no resident population at all in the modern census. The summer brings cars and small boats over from the mainland, families opening up the shutters and lighting the fires. The winter empties it again. The lights from the holiday windows are visible from Arranmore in season. After September, the dark returns.

The channel between Inishcoo and Rutland Island, just to the south, is the narrow passage that the Arranmore ferry uses on its run from Burtonport. The skippers know the islands and rocks of the Rosses intimately, the names of every reef and gap, where the tides run hardest, where the cross-currents catch you in a southwest gale. The channel is part of the visual landscape of the trip: islands close enough on both sides to see individual stones on their shores. The channel between Rutland and Inishcoo and the more open water beyond, with Arranmore filling the western horizon, is the geography that makes the Rosses a distinct kind of place. Not quite mainland, not quite island, a labyrinth of small land masses in shallow Atlantic water. Inishcoo is one node in that network.

There is not much published about Inishcoo. The Placenames Database of Ireland records the Irish name as Inis Cú. The cottage that stands largest on the island has its own website, advertising itself as accommodation for those who want a Donegal island all to themselves for a week or two. The historical residents are recorded only in census forms and parish baptismal registers. The shape of the island, however, is the same shape it has always been. The granite is the same granite. The view from the southwest corner across to the Rosses mainland, on a clear evening, with the lights of Burtonport coming on in the dusk, is the view that the coast-guard officers and the island's last permanent families would also have known. The Atlantic comes in. The Atlantic goes out. Inishcoo sits where it sits.