Depending on how long the eggs were in the cold water or if they were totally submerged, would determine the viability. There is the possibility that the eggs were in the water for a shorter time than when you discovered them and there was still enough air so that the embryos did not drown. Additionally, the top eggs may have been saved from being totally submerged.

Swan parents know exactly whether an egg is viable. They will kick rotten or infertile eggs from the nest. If the nest is near the water, they will actually take the egg and move it deeper in the water away from the nest so no predators are attracted. So, if the parents are still sitting on the nest and eggs, there is a good possibility that some if not all are viable. THANK YOU FOR DOING everything you did to at least give the eggs a chance. The Regal Swan