Aegir: God of the Sea
Aegir is the Lord & King of the Sea, Father of the Ocean. He is a sea-etin, or one of the jotunfolk, and considered to be one of the older Gods. He was the third, and youngest, son of a giant named Fornjotr or Mistarblindi. Aegir brews mead in a famous mile-deep kettle and hosts parties and gatherings for other deities, both the Aesir and Vanir, within his hall at the bottom of the ocean. He is famous for his hospitality, which he often uses for political reasons. His hall is lit brightly with shining treasures and gold, namely that from sunken ships, granting the use of the kenning "Aegir's Fire" for the brightness with which the gold shined. His hall was also considered a sanctuary of sorts, and is the place where the Gods met to discuss Baldr's death (the setting of the Lokasenna).
He often tends to be a jovial and welcoming deity. He is sometimes depicted as having a crown made of seaweed, skin that is blue-green, and green hair. He carries a spear as a weapon. Like other Jotuns, Aegir was still very-much a primal and chaotic elemental force. Aegir may give and take without judgment. He is the personification of the ocean: both the calm, gentle and warm waters and the violent, crashing darker waters. His mood is said to be able to turn quickly. His anger causes huge storms that crash ships upon rocks and drown sailors. When a ship was wrecked, it was said to have gone into "Aegir's wide jaws". Sailors and travelers often call upon Aegir before crossing his waters: whereas Njord is called upon for successful bounty of the sea, Aegir is called upon for safe passage. Sailors feared and respected Aegir, often making elaborate sacrifices to him. Historically, this sometimes included drowning victims from conquered lands.
Aegir is married to his sister, Ran, whose name means "robber" and who uses a net to drown people and bring them to her realm. Unlike Aegir, Ran tends to represent the more violent aspect of the ocean and is more vicious. Aegir and Ran had nine daughters, who are the nine waves, sometimes called the Wave or Billow Maidens and Undines. They represented different aspects of water and waves. Their names are as follows: Himinglaeva, Dufa, Blodhughadda, Hefring, Unn, Hronn, Bylgja, Bara, and Kolga.Those who die at sea are said to go to Aegir's Hall.
Giving Aegir food, such as bread, is said to be a good offering. This is namely because Aegir feeds the other Gods in his hall, and bread is not something he would normally get. Offering him mead and other alcoholic drinks is appropriate, but be warned! As a brewer, he takes offense to cheap and poorly made drinks. If you can, it is best to deliver the food directly into the ocean for him. If you do not live near the ocean, however, you can make a large bowl of salt water (to represent the sea) and drop the food or drink into that while invoking him. An invocation to Aegir may be something as simple as: "Hail Aegir! Husband of Ran. Ale-brewer. Gatherer of sea-gold. Father of the nine waves. Feast-friend of the Aesir and the drowned. Keeper of the great kettle!" (Norden).
Like Ran and their daughters, the Wave Maidens, Aegir also accepts gifts from the sea and its colors. You can use blues and greens for his altar, though darker colors would be more appropriate since he is associated with the depths of the water. Decorating his altar with gems and jewels, especially gold, is a good step towards gaining his favor. Things which have washed up from shore, such as shells and bits of bone, are good offerings or things to place on an altar. You can even collect these things in a jar, if you have a smaller offering space.
If you live near the shore, you can make a temporary altar out of sand that you let the waves wash away- taking the offerings directly to the Lord of the Sea himself. You can also make a floating altar, like the one Raven K describes for Ran: a mobile altar made of driftwood tied together. That kind of altar can sit on shelf space, and can be taken to a body of water whenever you go out. You could include sea shells, ribbons, dried fish, seaweed, coral and other things to represent sea life on it.
And, as always, since he is a jotun he appreciates hard work and effort. You may honor him by doing recreational activities within water, such as swimming, fishing, water sports, etc. Dedicating time to cleaning up the ocean, or offering money to organizations that do, is a fitting contribution.
Link to an article on Ran
Link to an article on the Wave Maidens
A Practical Heathen's Guide to Asatru by Patricia Lafayllve
Heathen God, Goddess and Wight Invocations by Ingeborg Norden, Volmarr Wyrd and Amarina
Jotunbok by Raven K