geese on a mission

I saw the strangest thing today. As I was looking out at the river this morning I saw 20 geese swimming by. Now I'm used to seeing geese fly in formation, making their perfect V but I've never seen them do synchronized swimming before. In fact I hardly ever see more than two or three on the river at a time. 16 of the geese were swimming along in a perfectly straight line, one behind the other, very slowly and sedately while 3 swam along side at a little distance and one (the 20th) came swimmng along a little bit behind the rest. If it had been cars on a road I would have guessed a funeral procession. Being curious, I googled 'geese swimming in a line' and, to my amazement, several pictutes popped up, showing, you guessed it, geese swimming in a line. The only difference I saw was that all of the photographs showed an adult goose leading several goslings, while what I saw was a whole long line of same size geese. They swam the whole length of the river that I can see, east to west, and eventually went under the bridge and out of sight. I didn't see them come back so they may be swimming still, off on their mysterious mission.