Tobar na Croise, the Well of the Cross, was the site where rounds were formerly performed, the traditional circuit of prayers made around a sacred water source, specifically to cure sick cattle. That detail alone sets it apart from the more familiar pattern of holy wells associated with human ailments or patron saints. The well, known in English as Tobernacrusha, appears by that anglicised name on the 1842 Ordnance Survey map, suggesting it was already a well-established feature of island life at that point.

Alongside the ritual use of the water, there was once a cross-inscribed stone at the site, a carved marker of the kind found at many early Christian holy wells across Ireland, where the physical landscape was shaped to signal sacred significance. The writer known as An Seabhac noted its existence in 1939, and the folklorist Caoimhín Ó Danachair recorded further details in 1960, observing that the stone had stood at the well formerly, the past tense implying it was already gone or displaced by then. The well itself survives, though it is now enclosed within a concrete structure, a modest and functional intervention that replaced whatever earlier arrangement had existed. The Great Blasket was evacuated in 1953, when the remaining islanders were resettled on the mainland, and the well has stood without a community to tend it since.