Djupur

Djupur (plural Djupir) is a translation of the term "Deep One" from the Lovecraftian Mythos. The Djupir are a race of water-breathing, aquatic humanoids who rule vast cities underwater. They are not particularly friendly to humans or land-wights, but they do sometimes interbreed with them, producing hybrid Deep Ones. These beings can appear as relatively normal, if somewhat ugly, members of the land-dwelling species among whom they dwell, but some feel the "call" of the sea and become aquatic Deep Ones as they mature.

Source: Found in the writings of H.P. Lovecraft as part of his Cthulhu Mythos, known in Midhgardhur as the eponymous "Sons of Aegir, Daughters of Ran" (the title of a story in the Tales of Midhgardhur).