Merfolk

Merfolk are among the first fey to have emigrated from the fey realm to the mortal realm many millennia ago, making them one of the oldest races to populate Etheria. So ancient are the merfolk that, even before the pre-Etherians had encountered the Etherian continent, they had encountered this race of sea-dwelling fey folk along the shores of their homeland many centuries prior to The Draconic Exodus, though they likely had no conception of what fey were at that time. 
Merfolk dwell throughout the oceans and seas surrounding Etheria with a few populations taking up residence in some of its deeper lakes, exploring a world of coral forests and secret mountains the "dryfolk" of the surface world will never know. While most live their entire lives beneath the waves, they're not bound to the deep. Following their inherent curiosity, some merfolk venture beyond the depths, seeking to explore a whole world of wonders beyond their own.
Merfolk are an amphibious people, at home in the water but mobile on dry land. As a result, their bodies are highly adaptable, and often undergo a change in appearance depending on the environment they find themselves in. In their natural underwater state, merfolk are covered in fine scales that range from gray to yellowish-green through shades of blue to deep purple. Fins sprout from their forearms, calves, and shoulders, their ears are frilled and necks gilled, their canines are pointed and sharp, and their digits are webbed, allowing them to swim as quickly as they can run. On dry land, their scales recede to reveal flesh colored in any range of standard humanoid hue and their gills seal to be replaced by lungs. Their fangs, fins, and frills often remain. 
Well suited to life in the frigid deep or tropical waters, merfolk wear little clothing unless armored for battle. They fashion most of their clothes and other items from materials found in the ocean: coral, seaweed, shells, bone, sea urchin spines, the shells of monstrous crustaceans, and so on. Having an old, well-developed civilization, merfolk know much of how to refine these materials into garb as rich and weapons as sturdy as any found on land.
For centuries, dryfolk have fished the seas of Etheria and have used the sea's surface as a means of travel. Many merfolk interpret this as an intrusion into their domains. As a result, some warlike merfolk communities respond with periodic strikes against sailors and fishing vessels. Others believe that turnabout is fair play and so venture onto land to hunt for meat, steal supplies from coastal travelers, or raid dryfolk cities for riches.
Despite the tensions between merfolk and the peoples of the surface, some merfolk make their lives on land. Enchanted by the feeling of the winds, the rustle of leaves, the ingenuity of land-dwelling inventors, or any of countless other surface-world charms, every merfolk living beyond the waves does so for their own reasons. In some places, like the Elaeusian polis of Meleta, whole merfolk communities flourish among dryfolk neighbors.
While Etherian merfolk pay respects to many gods, they tend to revere Thalassakles the Crashing Wave, god of the sea, above all other deities. Her devotees see her as the primary god of The Etherian Pantheon, believing she will bring their people to ascendancy over the monsters of the sea and the cities of the land. 
Many merfolk are intrigued by surface culture. The curious among them venture into sunken ruins and shipwrecks, sifting through the debris for whatever grabs their attention. Often these merfolk develop collections of a specific kind of object or lore, trading with one another as they develop a sort of expertise in their field. Some merfolk approach investigations of the dryfolk with scientific rigor. Such scholars often hold theories to go along with their collections, hypotheses many are eager to test upon meeting new dryfolk.