This is Tobar Cholmcille, a holy well associated with Saint Colmcille, the sixth-century monk and scholar more widely known as Columba. What makes the spot quietly unusual is a shallower depression adjoining the rim of the main hollow, perhaps thirty centimetres across, said by local tradition to preserve the knee-print left by the saint himself in the rock.

Holy wells across Ireland were typically visited through a prescribed ritual known as a pattern or rounds, in which a pilgrim would walk a set number of circuits around the well, praying as they went. At Tobar Cholmcille, the practice involved seven such rounds, with a pebble cast into the water on each circuit. The number seven carries longstanding significance in devotional custom, and the casting of the pebble served as a kind of votive punctuation, marking each completed round. Tim Robinson, whose 1985 survey of Connemara recorded the well, noted that no offerings were visible at the time, though the site had been actively frequented within living memory of his writing. The well is positioned in Coill Sáile, a place whose Irish name suggests a tidal or salt-water wood, which adds a certain logic to a sacred site that exists at the margin between land and sea, caught between fresh water and the Atlantic.