The structure’s west wall rises impressively to three storeys, reaching 6.8 metres in height and stretching north to south. Short sections of wall extend from this main facade; the northern return measures 4.5 metres internally whilst the southern return extends just one metre inside. These weathered stones once formed part of a formidable stronghold belonging to the O’Mahony clan, one of the powerful Gaelic families who controlled much of this region during the medieval period.

The tower’s defensive architecture is stark in its simplicity, with only a single window surviving to hint at its original design. This opening, featuring a flat-headed light at first floor level in the north wall, would have provided both illumination and a vantage point for watching over the surrounding waters. The strategic placement on Castle Island allowed the O’Mahonys to monitor maritime traffic through Roaringwater Bay, one of Ireland’s largest natural harbours dotted with numerous islands and hidden coves.

Archaeological surveys conducted for the Archaeological Inventory of County Cork have documented these ruins as part of West Cork’s rich medieval heritage. Like many Irish tower houses of its era, this castle served multiple purposes; it was simultaneously a residence, a symbol of authority, and a defensive position in the complex territorial disputes that characterised Gaelic Ireland. Today, these fragmentary walls offer visitors a tangible connection to the O’Mahony legacy and the maritime history of this spectacular corner of County Cork.