Eastern River Cooters are capable of growing up to 16 inches (41 cm). The upper shell is typically dark greenish-brown with pale yellow markings. The skin is dark green with yellow stripes down the neck and legs. The bottom shell is yellow with a dark pattern that follows the scute seams. They are often confused with yellow-bellied sliders, which also have yellow stripes and yellow bottom shells, but the latter have green spots along their bellies.
As these turtles grow older, they tend to become very darker, obscuring much of the shell design. Wide, sometimes dark-edged, stripes under the chin form an upside-down “Y”. Males have a broader tail and may have a slightly concave bottom shell. Females tend to grow larger than males, and have a smaller tail and more convex bottom shell.