Inko is one of three living Sea Serpents.

Inko lives in a far away ocean, but he and his brother Unko visit their eldest brother Anko every hundred years. (The Sea Fairies)

There is some speculation that the A-B-Sea Serpent (The Royal Book of Oz) and the goblin-toothed serpent (Captain Salt in Oz) are Unko and Inko.