The structure runs roughly north to south, curving gently inward toward the island as it reaches the mid-foreshore. At around 180 metres long and just two metres wide, it is a surprisingly substantial piece of engineering for something so easy to overlook, with individual timbers surviving to heights of between three and four metres above the clay.

The jetty is post-medieval in date and appears on both Ordnance Survey maps and Admiralty charts, where it is associated with the island's harbour pilots. Quay Island's position on the Shannon estuary would have made it a logical base for pilots, who guided vessels through the navigable channels of one of Ireland's longest and most commercially significant rivers. The estuary's shifting sandbars and tidal conditions made local expertise genuinely essential for incoming ships, and a dedicated jetty of this scale suggests the pilotage operation here was no minor affair. The structure was recorded and described by archaeologist Aidan O'Sullivan in 2001, working from fieldwork carried out in August 1995.