Yet what befell him afterwards is known. As his birth was strange, so was his end, for he saw the wonders of the Land of Youth with mortal eyes and lived to tell them with mortal lips.
When the white horse with its riders reached the sea it ran lightly over the waves, and soon the green woods and headlands of Erin faded out of sight. And now the sun shone fiercely down, and the riders passed into a golden haze in which Oisīn lost all knowledge of where he was or if sea or dry land were beneath his horse’s hoofs. But strange sights sometimes appeared to them in the mist, for towers and palace gateways loomed up and disappeared, and once a hornless doe bounded by them chased by a white hound with one red ear; and again they saw a young maid ride by on a brown steed, bearing a golden apple in her hand, and close behind her followed a young horseman on a white steed, a purple cloak floating at his back and a gold-hilted sword in his hand. And Oisīn would have asked the princess who and what these apparitions were, but Niam bade him ask nothing nor seem to notice any phantom they might see until they were come to the Land of Youth.
The story goes on to tell how Oisīn met with various adventures in the Land of Youth, including the rescue of an imprisoned princess from a Fomorian giant. But at last, after what seemed to him a sojourn of three weeks in the Land of Youth, he was satiated with delights of every kind, and longed to visit his native land again and to see his old comrades. He promised to return when he had done so, and Niam gave him the white fairy steed that had borne him across the sea to Fairyland, but charged him that when he had reached the Land of Erin again he must never alight from its back nor touch the soil of the earthly world with his foot, or the way of return to the Land of Youth would be barred to him for ever. Oisīn then set forth, and once more crossed the mystic ocean, finding himself at last on the western shores of Ireland. Here he made at once for the Hill of Allen, where the dūn of Finn was wont to be, but marvelled, as he traversed the woods, that he met no sign of the Fian hunters and at the small size of the folk whom he saw tilling the ground.