Snorri Sturluson's Prose Edda preserves something the poetic sources only gesture at elsewhere: individual names for each of the nine daughters of Aegir and Ran, a set of personified waves used by skaldic poets as an entire vocabulary of ocean kennings. The list, given in the Skaldskaparmal, includes names such as Himinglaeva, sky clear, for the wave whose foam catches the light, Dufa, the pitching wave, Blodughadda, bloody haired, for a wave reddened by storm, Hefring, the rising wave, and Kolga, the cool wave, among others, each a poetic figure a skald could invoke to describe the sea's motion without ever naming the sea directly.
Old Norse court poetry prized this kind of indirection, building elaborate kennings, the sea as the field of Aegir, gold as the fire of the waves, out of a shared stock of mythological names that a listener needed to know in order to follow a poem at all, and the daughters of Aegir supplied some of the most productive material for exactly that purpose.
Later in the mythology, the nine daughters are sometimes identified as the mothers of the god Heimdall, said in one Eddic poem to have been born of nine sisters at the edge of the world, a genealogy that ties Aegir's family into the ancestry of one of the Aesir's own watchmen. Whether this reflects an old, coherent tradition or a late skaldic flourish is not settled among scholars, and the poem itself gives few further details.