Aegir was a god of the ocean and his anger caused the seas to storm.  He and his wife Ran hosted the rest of the Aesir in their hall quite frequently.  Aegir and Ran had nine daughters: Bara, Blodughadda, Bylgia, Dufa, Himinglaeva, Hefring, Hronn, Kolga and Unn.  These daughters were the waves of the ocean.

“Higher still bade Helgi
the deep sail be hauled.
No port gave shelter
to the crews;
when Aegir´s 
terrific daughter
the chieftains’ vessels
would o’erwhelm.”

-- The Poetic Eddas, The First Lay of Helgi Hundingcide