Seaborne

Inquisitive, sometimes arrogant and often tempestuous in emotion, these are the legendary offspring of mortals and the beautiful and fully aquatic merfolk of the deep ocean, sirens of the shoals, and spirits of the rivers and lakes.
Sired through passion or pact, the call of the water is deep within the blood of these folk and leaves a profound mark on their lives. Seaborne are sometimes found living among humans, orcs or elves in coastal communities or in small enclaves of their own where, for example, a fishing village once paid physical tribute to a primordial sea-god and its children. Many, of course, are fishermen, navigators and sailors. Others are delvers, plunging into the bowels of the world's darkest dungeons in search of lost tributaries and underground seas perhaps never before swum by their kind.
Unlike true merfolk, the Seaborne can live comfortably on land, though they do suffer in especially dry conditions and must drink copious water to keep themselves hydrated compared to other peoples. Underwater, their physical features transform to make their bloodline more apparent. Some can hold their breath for an extended period, but other individuals in whom the blood is strong can manifest gills and breathe underwater freely.
Held in a mix of awe and distrust by superstitious sailors and seagoing communities, whether a Seaborne is an omen of fortune or disaster varies from culture to culture and sometimes individual to individual. With such a mixed reception everywhere they go, Seaborne can be quite sharp-tongued and thin-skinned, and often have an inflated sense of destiny and difference even in a world where diverse races and creatures are a common sight. The sea's potent presence in their psyche occupies an almost parental space; domineering and distant all at once, a force that every Seaborne shall have to contend with for better or worse.