Most snakes, including rattlesnakes, will avoid trouble if possible. I have spotted rattlesnakes near a trail, after several people have passed, and they were just trying to hide. I have seen them surrounded by a group of people (who were not aware it was there) and the rattler was just trying to get away. Water Moccasins on the other hand are territorial and aggressive. I have been chased by them, I have seen them stand their ground in the face of several people. Their poison is not as dangerous as rattler's venom. Their smaller cousin the copperhead is fairly aggressive as well, and will strike at passersby. Their poison is much the same as the water moccasin, but they tend to like to live in places where people live (woodpiles, under houses, bushes in the yard). Most of the snake bites I have personally been aware of in the Southeast are copperheads, mostly because they are more aggressive and belligerent.