From Seeing Things (1991):
The annals say: when the monks of Clonmacnoise
Were all at prayers inside the oratory
A ship appeared above them in the air.
The anchor dragged along behind so deep
It hooked itself into the altar rails
And then, as the big hull rocked to a standstill,
A crewman shinned and grappled down the rope
And struggled to release it. But in vain.
‘This man can’t bear our life here and will drown,’
The abbot said, ‘unless we help him.’ So
They did, the freed ship sailed, and the man climbed back
Out of the marvellous as he had known it.