Well, with the coming of the new year IC, this would be the perfect opportunity to develop a festival that sort of comes along with the idea of the new year, a rebirth, especially after the valterrian as it was the event that gave the svefra the Suvan sea. With the end of one thing comes the birth of another, and that is definitely reason enough for the bored svefra to celebrate. I'm taking this to development!
As for what people sacrifice to Laviku, well, anything really. Money, valuables, part of a fisherman's catch, items, anything. I'm sure he has hus preferences, but I'm not quite sure what they are, so I just throw whatever's in my hands into the sea when I feel like praying.