At certain times we used to see rafts of cotton mouths in a few lakes in NC. Coulda been a couple hundred of them in one raft, maybe more. Hate to fall into that mess. I hooked one while fishing for crappie. He did indeed try to climb up my leader and line to get to me. First time I ever cut a fly line. I let him have the fly, leader, about 15 feet of line and the whole pond.