Cottonmouth vs Water Snake — How to Tell Them Apart

This is the best tell from the bank. Cottonmouths float high and buoyant, with most of the body riding on top of the water and the head held up. Water snakes swim with the body mostly submerged and only the head and neck above the surface.

Cottonmouths have a heavy, blocky, triangular head that is clearly wider than a thick neck. Water snakes have a narrower head, but they flatten it into a triangle when threatened, so use this clue alongside the others.

Cottonmouths have a dark 'mask' stripe running from the eye back toward the jaw, often bordered with a pale line. Water snakes usually lack a bold mask, though some have dark bars on the lip scales instead.

Up close, cottonmouths have vertical, cat-like pupils and a heat-sensing pit between the eye and nostril. Water snakes have round pupils and no pit. Only check this in a zoomed-in photo, never by getting close.

Cottonmouths often stand their ground, coil, and gape to show the bright white inside of the mouth, which gives them their name. Water snakes almost always flee into the water and, if grabbed, bite repeatedly and release a foul musk.

Cottonmouths live only in the southeastern US, from southeastern Virginia to Florida and west into central Texas, north to southern Illinois. Any 'water moccasin' seen in Ohio, Pennsylvania, New York, Michigan, or New England is a water snake.