This underground passage, which extends approximately 8 metres from east to west, creates a subtle but noticeable linear depression in the landscape. The structure appears to run from the cashel’s eastern wall into its interior, though it remains unclear whether it continues beneath the ruined stone enclosure itself.

The eastern end of the souterrain preserves its most intact section; a 4-metre stretch of drystone passage topped with stone lintels that has survived largely unchanged through the centuries. While this portion remains structurally sound, access is no longer possible, leaving its depths unexplored in modern times. The craftsmanship of the original builders is still evident in the careful placement of stones that have held their position despite the passage of time.

Moving westward from this preserved section, the souterrain’s path can still be traced as a grassed-over depression in the earth. This shallow channel, measuring roughly 4 metres long, 1.5 metres wide, and up to half a metre deep, marks where the remainder of the passage has collapsed and been reclaimed by the landscape. The entire feature serves as a reminder of the sophisticated defensive strategies employed by early Irish communities, who used these hidden passages for storage, refuge, and strategic advantage during times of conflict.