Summary of site:
This cave, extending over 200m, has two entrances which are independently named. The upstream entrance, Mastodon, has two interconnected crawls through a boulder-choked rift that enter a mud-choked chamber, about 20m wide and 90m long, with numerous small streams entering through fissures. These join the main subterranean flow of the Sruh Croppa River.
Pollasillagh, the second entrance, opens into the northern (downstream) end of the chamber. Entry is by a small, boulder–covered hole in a modest depression and descends over boulders to an 8m descent to the chamber floor. At this end of the chamber there is a mazy crawl through more boulders to a flooded rift. A duck leads to a small chamber and sump.
Mastodon was almost certainly linked with Pollthanarees and Cat’s Hole upstream and with John Thomas’s Hole downstream but is now divided by local roof collapses.