Njord married Skadi, goddess of winter and hunting. Skadi chose her husband by observing the feet of the gods, without seeing their faces, and started looking for the cleanest and most beautiful feet, and chose Njord's, because his feet are always clean because of the sea water.
Njord and Skadi did not have a happy marriage, and soon separated, because Skadi as a mountain goddess could not live on the ocean shores just as Njord could not live in the mountains, with the constant change were created the seasons.
The god Njord is mainly known from the Snorra Edda, the Ynglinga saga and some Edda songs (Vafþrúðnismál, Lokasenna, Grimnismál), i.e. the high medieval learned mythography of Snorri.
There are also a few ritual formulas in which his name appears. In Aris Íslendingabók Njörðr is the second name in the Ynglinga genealogy. To this form of name is added the name Nerthus, handed down by Tacitus.
Place names that mostly use the genitive singular (Njarðar-) are mainly found in eastern Sweden (Östergötland), in eastern Norway and in the coastal areas of western Norway.
The connection Nerthus and Njord raises problems, since Tacitus is dealing with a goddess whom he assigns to a smaller tribal group within a narrowly defined geographical area. In addition, there is the large temporal gap between Tacitus and the Scandinavian sources.
There Njord is a male god. To these problems there is a multiplicity of theories. Sometimes Nerthus had spread gradually to Scandinavia, sometimes it was an all-Germanic god from the beginning. In former times the u-declination for masculine and feminine words was the same, but the feminine u-declination gradually died out in Scandinavia, whereby Nerthus became the masculine god.
Also it is represented that it had been in truth a pair of gods, of which in Tacitus only the important Nerthus had been mentioned. In the Edda then the male partner had come to the foreground, and the female had been modified to Skaði. Recently this connection between Nerthus and Njord is questioned (Simek, p. 147; Motz).