Some draw the parallel of the Sea Tsar with the tale about South Slavic morski kralj[1] recorded, e.g., by Slovenian poet and ethnologist Matija Valjavec [sl] in his 1890 collection Narodne pripovjesti u Varaždinu i okolici (Folk Tales from Varaždin and its Vicinity),[2] also published by Franc Hubad [sl] in his Pripovedke za mladino collection (referring to Valjavec).[3] The tale in question (in both references) is called "Čudotvorni lokot" ("Magic Padlock").
Andrijana Kos-Lajtman and Jasna Horvat notice that in the tale "Magic Padlock" the sea king is not written with capital letters and there is nothing particular of sea surroundings, i.e., the sea is not a determining feature of the tale. It addition it turns out that the sea king also has a cat, clearly a non-maritime animal.[4]
This is a story about a young man who rescues a dog, a cat, and a snake. Snake's mother gives him a magic padlock which fulfils his wishes. The padlock helps him to win the (land) king's daughter for a bride. A sea king comes to visit the (land) king, notices how the young man operates the padlock, steals it, and orders to bring the castle and the bride to the sea. The cat and the dog steal the padlock back, the young man wishes the castle and the bride back, and the sea king as well, whom they roast on a spit.[3]
Another sea king (morski kralj) is in the elaborate literary fairy tale Ribar Palunko i njegova žena (Palunko the Fisherman and His Wife) by Croatian writer Ivana Brlić-Mažuranić.[5] However her Sea King has nothing in common neither with that of Valjavec, nor with the Sea Tsar from the East Slavic folklore.[4]