Inishtrahull, Co. Donegal

Ireland's most northerly island. I visited Inishtrahull once, in 2013, aboard the Irish Lights helicopter. We were working our way along the coast after a brutal winter of storms, surveying lighthouse stations for damage, and this was our last stop.

The island was abandoned in 1929, when the last families were taken off. Nearly a century later, the lighthouse and its buildings still stand, white and sharp against dark Atlantic rock. What surprised me when we landed was how slim the tower is compared to most Irish lighthouses. It's elegant in a way you don't expect from something so purely functional. The Commissioners of Irish Lights still maintain that white paint, and against the grey-green grass and black rock, it almost glows.

I took this from the helicopter as we came in. The swell was running hard, breaking white around the island's edges, and the light was that diffused blue-grey you get under heavy cloud with just enough of a break to give the scene depth. From above, you see everything at once. The isolation, the exposed rock, the small cluster of buildings that once housed keepers and their families through Donegal winters. Hard to imagine.

I've been fortunate to visit quite a few of Ireland's offshore lighthouses, but this one stays with me. That slim white tower, still doing its job out beyond Malin Head. I find that very moving!