Hydrophis cyanocinctus has medium-sized, broad, and slightly depressed head with small eyes. There are 5-6 maxillary teeth behind the fangs. Head color is olive, reddish, or pale yellow. It has Imbricate scales with rounded or blunt tips at the thickest part of the body. There are 27-35 scale rows around the neck and 37-47 scale rows on the widest part of the body. It has 290-390 ventral scales. Bright coloration in young snakes, with captive-born snakes often being saffron yellow with black stripes.