Definitely something IN the water - not ON the lens. But more likely a picnic tabel or box or something blown in by the mini hurricane served up last week. Doesn't seem to have moved much if at all in the week it has been there....but it is definitely just off the deck closer to the shore - and under the water. From the orange gate draw a line with your finger parallel to the frame - and you'll come to the yellow box - ripples on it - so it's not a lens blemish.