Knocking in Dickenson County, Virginia

At around 11pm on July 26th my wife and I we're night fishing on the backwater of cranesnest river in Dickinson county Virginia. My wife's head was hurting so she decided to take a nap we had heard something large walking in the woods but wrote it off as a bear or deer as both are plentiful in our area. She had been asleep for about an hour when I heard a large knock about 50 yards up in the tree line then about 15 to 20 seconds later several hundred yards up the ridge there was another knock. Both sounded as if someone had taken a 4x4 post and struck a tree with it. Then about 10 min later there was a splash in the water about 20 feet away from our boat. This splash sounded like something weighing 20 or 30 lbs had struck the water waking my wife. It's not unusual to hear large fish jumping at night but this was different after the splash no more than a couple minutes had passed and there was 2 more knocks. And they were closer than the first one. We pulled anchor reeled in our lines and as we were leaving we heard 2 more knocks. My wife said she heard the knocks up on the ridge but I didn't hear those, just the sound of a large animal walking up the river same way we were traveling as if it was following us. When it came to a shallow cove where it would have had to swim we stopped hearing the walking sounds. This is the second time we encountered this animal we had an experience about a month and a half earlier we heard a big animal walking around and had big splashes in the water as if it were throwing things at us on that night as well.