It is a navigation beacon, one of three that together once guided vessels safely through the bay, and its placement is deliberate: it sits almost directly opposite Cromwell's Fort on the southern shore, the two structures bracketing the harbour entrance like a pair of mismatched sentinels. What makes this particular tower quietly arresting is not its function alone but its details. Cut into its south-western face is a niche housing a statue of the Blessed Virgin Mary, a devotional addition that speaks to the overlap, common enough along the Irish Atlantic coast, between practical seafaring infrastructure and religious life. At the base of the wall, on the western side, a small inscribed stone commemorates a Hugh O'Donhel; it carries no date, and nothing more is recorded about him.

The tower itself is built from roughly coursed masonry, rendered and lime-washed to maximise visibility from the water, which was precisely the point. Its base has a slight outward lean, known as a batter, extending about 0.32 metres wide and 0.4 metres high, a common structural technique in vernacular masonry to add stability at ground level. The shaft tapers gently upward to a projecting cornice, and above that, two stepped bands of dressed ashlar masonry, stone cut and finished to closer tolerances than the rougher courses below, form the cap. The contrast between the utilitarian lower construction and the more carefully finished top is characteristic of functional maritime structures where the upper portion needed to present a clean, recognisable silhouette against the sky. The beacon commands panoramic views across the water from east-north-east to west-north-west, confirming that its siting was carefully chosen for maximum sightline coverage of the approaches to the harbour.