This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Umi-nyobo (Japanese)
Umi-nyobo a live in the ocean and resemble human women, but have many fishlike features. Their skin is scaley like a fish, and their fingers and toes are webbed like a waterfowl’s and resemble fins. Their teeth are sharp and brilliant, like a shark’s. They are very strong, and very dangerous.
Umi-nyobo spend most of their time in the oceans. However, they are able to survive on land for several days without returning to sea. According to an entry for Umi-nyobo in the Yamato honzo, a biology encyclopedia written in 1709, they are unable to speak. However, many folk tales depict Umi-nyobo who are able to speak.