Pollnagollum-Coolarkin is situated in Belmore Forest in the parish of Boho. It is located a little over a kilometer south of Boho Cave. Similar to Boho it is fed with run-off from the northern flanks of Belmore mountain. This culminates in a dramatic 12m waterfall that plunges over the large but gently inclined doline of Coolarkin.
As one walks down the doline a high and wide entrance leads into a cave that only increases in size, becoming up to ten meters in width and opening up as a single tunnel-like passage of enormous proportions.
The stream now meanders, taking a course predominantly on the left hand side and sinking at a boulder pile. The cave runs fairly straight on a NW-SE axis and features numerous minor cave features such as an aven and some almost hidden cave pearl pools. The loftiness of this cave is somewhat unparalleled in Ireland, but here it ends. Unfortunately, after 200m an enormous collapse of boulders closes the cave off completely.
From this point on all we know is based upon water tracing tests, which have established its resurgence almost two kilometres south (Jones et. al., 1997). Many (myself included, briefly) have tried to dig an advance through the boulder pile but it is highly discouraging due to the endless quantity of enormous boulders which appear to be only lightly cemented together in thin laminations of soil.
The prospects of what might lie beyond the collapse are obvious and yet to be realised but any gain seems almost impossible. Until then, Coolarkin will wait, enticing and frustrating cavers for quite possibly a few generations more!
references
Jones at. al., 1997. Caves of Fermanagh and Cavan. Florenececourt, Fermanagh: Lough Nilly Press.
Caves Of Ireland 