Bayble Island sits at the southern end of Bayble Bay - in Gaelic, Pabail Bay - on the long southern shore of the Eye Peninsula. The peninsula juts east from the main body of Lewis, tied to it by a low neck of sand at the famous Braighe. Bayble itself, both Upper and Lower, is one of the larger settlements out on the peninsula, the sort of place where the road bends along the bay and houses face the water and nothing much has changed about the shape of the land in a thousand years. The island in the bay is the kind of landmark every village around it has used to orient itself, named in the local language long before any chart recorded it.

The geography is a quiet trick. Eilean Mòr Phabaill - the bigger of the two - and Eilean Beag Phabaill - the smaller - lie close enough together that from the village above, or from a passing boat, they merge into a single silhouette. Gaelic place-names sometimes encode geological precision: mòr and beag mean big and little, and the names sort the islands neatly even when the eye refuses to. The split is visible only from certain bearings and certain heights. From the air, the channel between them is unmistakable; from sea level on the Bayble road, the two become one.

The island is uninhabited and stays that way. Rats are believed to live on it - thought to have arrived from a shipwreck, the same folklore that explains the rats on the Shiant Isles further south, though whether the story is history or invention is anyone's guess. Above the water, the air belongs to gannets. The northern gannet, with its near two-metre wingspan and its astonishing diving habit, can be seen plunging into the surrounding waters from heights that would kill anything less aerodynamically perfect. Other seabirds work the bay too. The Atlantic comes onshore here in its everyday form: not dramatic, just enormous and patient.

There is no causeway, no ferry, no reason to set foot on Bayble Island. Its role is to be seen, not visited - a fixed point in the geometry of the bay, a landmark for boats heading in and out, a foreground for the dawn from Upper Bayble. The smaller hamlets along this coast have lived alongside the island for generations, and the relationship is the one Hebridean settlements have with their offshore rocks everywhere: deeply familiar, vaguely mythological, mostly silent.