Poll na bPéist, Ireland’s naturally rectangular rock pool

2 min read

Inis Mór (Inishmore), the largest of Ireland’s Aran Islands, is home to a remarkable natural wonder know as Poll na bPéist, a rectangular pool cut so straight into limestone that it looks man-made, carved by the sea in the limestone rocks of the island, creating a stunning contrast between the turquoise water and the grey stone.
Also known as “The Wormhole” or “The Serpent’s Lair”, it is a natural water basin with an edge length of around 10 by 25 meters within a stone formation.

It is located on the west side of Inis Mór, about 1.6 km south of the ancient cliff fort of Dún Aonghasa, and you can reach it by following the signs from Gort na gCapall, a small village near Kilmurvey Beach, or by walking along the cliffs from Dún Aonghasa, where you will see painted rocks indicating the way, and in recent years it has become famous for hosting the renowned Red Bull Cliff Diving World Series in 2012 and 2017.
The divers jumped from a platform 28 metres above the water into the narrow opening of the pool, performing impressive acrobatic feats.

The unusual formation also features underwater channels that connect to the sea.
Water flows into Poll na bPéist through a subterranean cavern, or sometimes waves crash over at high tide, filling it from the top.
The pool is around 300 meters deep and features underground channels through which the currents surge and retreat from the open sea, threatening to suck unsuspecting swimmers into the ocean.
Its most fascinating thing is its remarkable rectangular shape, which has led many to question its natural origins and sparked several theories, including that it is the work of an ancient civilization.
According to the legend, the pool is actually a serpent’s lair, and some locals believe that it has healing properties.
Either way, as hard as it seems to believe, Poll na bPéist formed naturally, through the erosion of deeper layers of limestone along straight edges.