Slipped a piece of hardware cloth over the barrel of lens to protect myself in case the snake tried to bite. These guys are very peaceful. I see them nearly every-time I photograph in the river bottoms in the area. Slitted pupils and a triangular head with a pit indicate the snake is poisonous.
These are way beyond the haphazard snapshots I have from vipers. There is only one poisonouse species in Finland (vipera berus), and I haven't seen a specimen that stays put to have its picture taken. They are usually very shy and flee to underground holes. Our vipers swim but it is common belief that they cannot strike from water. Yours looks like it's ready to strike at any time.
Very nice Tom! One emerged from the water at Cross Dike on Sanibel Island many years ago, and was surprised that my wife was in its path. I was impressed with the size of it and the speed it could move on the sand.