It is easy to miss entirely. A few stones piled loosely on the rock are the only marker, and the well itself is a natural pothole no wider than a hand's breadth, roughly a quarter of a metre across. Inside it, coins have accumulated over time, left by those who knew what they were looking at.

The well is known locally as Tobar Cholmcille, meaning the well of Colm Cille, the sixth-century saint also known as Columba, who is associated with holy wells and sacred water sources across Ireland and Scotland. Holy wells, sites where natural water sources were venerated, often predate Christianity and were absorbed into the Christian tradition, frequently acquiring the name of a local or nationally significant saint. The name here was recorded through local knowledge passed on by Tim Robinson, the writer and cartographer who spent decades mapping and documenting the human and physical landscape of Connemara and the Aran Islands. That the well carries Colm Cille's name at all, on a small island off the Connemara coast, suggests a devotional geography that once reached into surprisingly remote places.

Because the well sits at the low-water mark, it is only accessible at low tide, and the coins inside it have presumably been deposited by people who came specifically at that moment. The piled stones nearby are modest to the point of invisibility, which means finding the spot requires either local knowledge or careful attention to the rock face as the tide recedes.