First discovered in 1978 by cave diver Martyn Farr, the cave was explored to a depth of 103 metres (338 ft) underwater by Artur Kozłowski, one of Farr's students, on 5–6 July 2008. Following Kozłowski's death in 2011, the cave was entered again by Michal Marek, who pushed the depth to 113 metres (371 ft).
The cave is located in the Partry Mountains in the townland of Bellaburke near Killavally, Westport, County Mayo, where the Aille River reemerges, having gone underground at Aille caves some 4 kilometres (2.5 mi) away. The cave entrance is on privately owned farmland.
The explored limit of Pollatoomary is also 23 metres (75 ft) deeper underwater than that of the terminal sump in Wookey Hole Caves in Somerset, England, which had previously held the record for the deepest underwater cave in Britain and Ireland.
- "Polak zginął podczas nurkowania w Irlandii". wbi.onet.pl (in Polish). 16 May 2019. Retrieved 2019-05-18.
- Siggins, Lorna (7 September 2011). "'There is no rescue - only recovery, if you're lucky'". Irish Times. Retrieved 27 June 2012.
- Kozłowski, Artur (2009). "Dark Rising: the exploration of an underground river in County Mayo, Ireland". Irish Speleology. Speleological Union of Ireland. 18: 69–70. ISSN 0332-4907.
- Gallagher, Emer (16 July 2008). "Explorer plunges to new depths in Mayo". Mayo News. Archived from the original on 7 December 2013. Retrieved 21 September 2011.
- Siggins, Lorna (August 7, 2008). "Cave explorer plumbs new depths in Mayo". Irish Times. Archived from the original on 3 December 2008. Retrieved 13 January 2017.