Their whole life was the sea, the sea and their boats. So in celebrating their deaths- yes, you can say celebrating - they used both. The families of the great Viking would put the body of their loved one on a ship, cover it with straw, and then, as the sun was setting, cast it away into the water. They would light huge bonfires on the beach, and then the Vikings would light the tips of their arrows in the bonfire and shoot them at the ship. Ah, it must have been so beautiful, fire on the water...