They are also known as a Water Moccasin. For a snake they can grow large, 35 in (90cm) and occasionally 71 in (180cm). These are venomous snakes, so a really large one can be fatal.
Around marshes and swamps they are common, and thankfully shy. We surprised this one while driving down a dirt marsh road. He jumped almost straight up into the dead leaves.
The angle was not great for a shot. I didn’t want to get in front of him or ask him to pose differently. We took a few shots and went on our way. After all, he was there first.