The airship of Clonmacnoise is the subject of a historical anecdote related in numerous medieval sources. Though the original report, in the Irish annals, simply mentioned an apparition of ships with their crews in the sky over Ireland in the 740s, later accounts through the Middle Ages progressively expanded on this with picturesque details. First the ships were reduced to one ship over Teltown from which a crewman threw and then recovered a fishing-spear. Then the scene shifted to the abbey of Clonmacnoise, and later to Britain, and the fishing-spear was changed to an anchor which snagged on some feature of a church. The sailor who climbed down to release it was also said to be in danger of drowning in the thicker air of this lower world. The story was retold by Seamus Heaney in a well-known poem collected in his 1991 volume, Seeing Things.