Cottonmouth snakes are a regular sight and hazard along the rivers, lakes, and swamps of the southeastern United States. Excellent swimmers and climbers, cottonmouths are a potential danger to everyone who wants to enjoy the many recreational activities the southern waterways afford. Some even fall into boats passing under trees! Watch this video to learn more about these venomous snakes also known as water moccasins, and find out just how big they can get.