Seeing a Cottonmouth this size, would make even the most experienced outdoors-man give it a wide berth. Whether you are a fan of snakes, or not, this certainly is one video you should watch. When I was in the U.S. Army and stationed in the southeastern part of the country (Texas, Georgia, Alabama and North Carolina), I came across quite a few venomous snakes in my time.
Rattlesnakes, Coral snakes and even Water Moccasin’s (aka Cottonmouth). At least the rattlesnake will give you a quick shake of the rattles in his tail as a warning if you get too close, but the other two snakes won’t. The Coral snake has it’s brights color pattern to give a visual warning to any would-be predators who might want to bother it. So that leaves us with the cottonmouth. This snake when come upon in the wild, some say, will not retreat when confronted, others say, that they’re really aggressive, but not as a rule. When they feel threatened they will often open their mouths and display their fangs as a warning. Often found on, or near water, the cottonmouth is a semi-aquatic viper and is a strong swimmer. As a rule, these animals won’t bother you, unless you bother them.
According to Wikipedia: