When water levels drop, a narrow trench, just two metres long and barely sixty centimetres wide at the surface, reveals itself as the entrance to an underground chamber below: roughly two metres high, two metres wide, and at least three and a half metres in length, partially backfilled but still accessible. For most of the year, the flooding conceals every trace of what lies beneath, and there is nothing visible to suggest that anyone was ever here doing anything at all.

The site is a copper mine, and its age is not recorded, though the most telling clue to its origins sits in the spoil heap nearby. Spread across an area of roughly twenty metres square, the heap contains numerous broken stone mining mauls, hammerstone tools used to break and extract ore before metal implements became standard practice. Their presence points toward prehistoric workings; Bronze Age copper mining using stone mauls is well attested in Ireland, most famously on the Beara Peninsula not far from here. What makes An Ráth particularly curious is the absence of any obvious copper mineralisation remaining at the site. The ore, if there was a seam worth pursuing, has either been exhausted or was never as substantial as whoever sank that trench had hoped.