It measures approximately 23 metres north to south and just under 15 metres east to west, and at first glance it reads as a purely natural feature. Look more closely at the walls, however, and a different story emerges: drill runs score the rock face all the way around the interior, the unmistakable signature of human industry rather than geological accident.

The prevailing interpretation, drawn from C. Toal's North Kerry Archaeological Survey published in 1995, is that Poultarrif was worked as a lead mine. Miners appear to have exploited the blowhole, a naturally formed shaft where wave action or collapse has opened a vertical cavity in the rock, as a ready-made shaft or access point for extracting ore. The working continued until the natural processes that formed the hole in the first place reasserted themselves, causing the mine to collapse. The site sits roughly 90 metres east of a sub-rectangular enclosure, and the two features may be connected, though the precise relationship remains uncertain. It is a telling example of how industrial and natural history can become entangled: the same geological violence that created the void eventually reclaimed it.