This species differs from all other North American water snakes by having one or more small scales under the eye, giving the appearance of a ring of small plates around the eye. These heavy-bodied snakes are dark green, olive, or brown dorsally. Ventrally they are yellowish on the anterior third, and the on remainder they are dark brown with yellow or white semicircles. They average 76-140 cm (30-55 in.) long; record, 188 cm (74 in.) for a specimen of N. c. floridana.