Away they went and they got to Greece, and he went in to the palace and did as the black horse bade. He took the cup and came out and mounted, and before sunrise he was in the Realm Underwaves.
"We had better get married now," said the prince to the Greek princess.
"Slowly and softly," said she. "I will not marry till I get the silver ring that my grandmother and my mother wore when they were wedded."
"You, rider of the black horse," said the Prince Underwaves, "do that. Let's have that ring here to-morrow at sunrise."
The lad went to the black horse and put his elbow on his crest and told him how it was.
"There never was a matter set before me harder than this matter which has now been set in front of me," said the horse, "but there is no help for it at any rate. Mount me. There is a snow mountain and an ice mountain and a mountain of fire between us and the winning of that ring. It is right hard for us to pass them."
Thus they went as they were, and about a mile from the snow mountain they were in a bad case with cold. As they came near it he struck the horse, and with the bound he gave the black horse was on the top of the snow mountain; at the next bound he was on the top of the ice mountain; at the third bound he went through the mountain of fire. When he had passed the mountains he was dragging at the horse's neck, as though he were about to lose himself. He went on before him down to a town below.
"Go down," said the black horse, "to a smithy; make an iron spike for every bone end in me."
Down he went as the horse desired, and he got the spikes made, and back he came with them.
"Stick them into me," said the horse, "every spike of them in every bone end that I have."
That he did; he stuck the spikes into the horse.
"There is a loch here," said the horse, "four miles long and four miles wide, and when I go out into it the loch will take fire and blaze. If you see the Loch of Fire going out before the sun rises, expect me, and if not, go your way."
Out went the black horse into the lake, and the lake became flame. Long was he stretched about the lake, beating his palms and roaring. Day came, and the loch did not go out.
But at the hour when the sun was rising out of the water the lake went out.