King Kojata or The Unlooked for Prince or Prince Unexpected is a Slavonic fairy tale. Andrew Lang included the Russian version King Kojata, in The Green Fairy Book. A. H. Wratislaw collected a Polish variant Prince Unexpected in his Sixty Folk-Tales from Exclusively Slavonic Sources, number 17. A shorter, also Polish version, The Unlooked for Prince, was collected by Louis Léger in Contes Populaires Slaves and included by Andrew Lang in The Grey Fairy Book. Josef Baudiš published Czech version in English, named Kojata, in his book of Czech folk tales The Key of Gold in 1917 (reprinted 1922). Another version of the tale, titled Kojata, appears in A Book of Wizards by Ruth Manning-Sanders.
A king and a queen had no children. One day, the king was travelling (hunting to forget his childlessness in the Polish, inspecting his country in the Russian), and grew thirsty. He found a spring with a cup floating in it. Trying to grab the cup did not succeed; it always evaded his hands. When he dropped to drink directly, a creature in the well (the King Kostiei in Polish,) grabbed his beard and would not free him until he promised to give it something: in Polish, the most precious thing in his palace, which was not there when he left it; in the Russian, something he knew nothing about, and which he would find on his return home.
He promised. On his return, he found his wife had had a son. He told no one of the exchange, but when the prince was grown, an old man appeared to him in the woods and told him to tell his father to make good on his bargain. When he told the king, the king told him the truth. The prince set out to pay it.
He came to a lake where thirty ducks (Russian) or twelve geese (Polish) were swimming, and where there were clothes on the shore. He took one. The birds came ashore, changed into women, and dressed themselves, except the one whose dress he had. That one, as a bird, looked about, and begged the prince to give her back her clothing. He did so. She was grateful, told him that she was the youngest daughter of the man he had been promised to, and promised to aid him. She told him that when he reached her father, he was to approach him on his knees, without any fear.