Aegir -the sea- as his brothers Kari -the air- and Loki -fire, were all supposed to have come from the older dynasty of the gods,
Aegir was not ranked with the AEsir, those gods of the North who were the pillars and supporters of the world. Or the Vanas, the sea and wind gods, and not the giants, dwarfs, or elves.
Aegir was considered omnipotent, all powerful, within his realm of the seas. He was generally likened to a gaunt old man, with thin hollow cheeks and a long white hair and beard and clawlike fingers ever clutching and moving convulsively, as though he was trying to have all things within his grasp.
It was said that he could cause great storms, the tempests which swept over the deep, and also calm the waters.
Whenever he appeared above the waves it was only to pursue and overturn ships and then drag them to the bottom of the sea.
I imagine maybe the clutching fingers were the waves constantly grasping the surface waters. The face of the old man of course would show the darker deep hollows beneath the sea's surface and his white hair and beard could have been the snow covered land and glaciers of the cold Northern world.
source -Myths of the Norsemen From the Eddas and Sagas published 1908 H.A. Gueber
