Baum said that they are the most beautiful creatures in the world, with the form of a lovely lady from the waist up and a fish from the waist down and scaled wings on their backs that look like two large fish fins. Since their race is older than that of both fish and mankind, they say that people are like mermaids without tails. Their hair is long and soft and silky, and floats around them in the water. They wear exquisite veils made of a sheeny silk material. The trains of their veils are so fleecy and transparent that the sparkle of their body scales can be seen through them. Many wear strings of pearls around their necks, and pearls are also used to trim their veils and lower fins.
A peculiar quality of mermaids is that no water ever really touches them. A thin layer of air surrounds their bodies and clothes, keeping them warm and dry and giving them air to breathe. It also protects them from the crushing weight of the water around them.
Since they are fairies, mermaids live forever, although they always appear young and beautiful. The mermaids are ruled by Queen Aquareine, and other notable mermaids are Clia and her cousin Merla. They are good friends of the Sea Serpents, and are enemies of the wicked Zog.
The Sea Palace
The mermaids live in an extensive palace at the bottom of the sea. It is surrounded by a grove of sea shrubs in a variety of gorgeous colors. Some are purple shading to lavender, reds from rose-pink to scarlet, and orange, yellow and blue shades mixed with sea-greens in a charming manner. The sea shrubs are set close together but several avenues lead into the groves, each guarded by several swordfish.
The gardens contain fruit bushes and sea flowers of exquisite colorings. Some resemble orchids in their shapes and hues.
The palace itself is build of white, pink, and yellow coral. There are no windows, but a series of archways serve as doors. At night it is lit by electric jellyfish; the mermaids have been using electric lights thousands of years longer than humans.
The main hall has walls of pink coral inlaid with white. To admit light, the roof is made of glass, created by the fairy powers of Queen Aquareine. The glass of the kitchen roof is curved so that it concentrates the heat of the sun, allowing the mermaids to cook food underwater.
The queen's throne room is the grandest and most beautiful chamber in the palace. Its coral walls are inlaid with mother-of-pearl, shaded and made into borders and floral decorations. Corner cabinets contain many curious shells beautifully polished. The floor glitters with gems arranged in patterns like carpet. Near the center of the room is a raised platform with a couch studded with diamonds, rubies, emeralds, and pearls.
The palace has guest rooms like the one used by Trot during her visit. The walls are covered with iridescent shells polished to resembly mother-of-pearl. Electric jellyfish are clustered on the glass ceiling for light. A couch covered in soft amber sponges stands in a corner, surrounded by gossamer draperies hung from four high posts. (The Sea Fairies)
Somewhere in the Land of Oz is Mer City which is a Merpeople colony. The Merchildren are taught letters by the A-B-Sea Serpent while the Merbabies are watched over by a friendly Rattlesnake. (The Royal Book of Oz)