The dangerously venomous Hydrophis obscurus is known from coastal waters of Myanmar, especially of the Ayeyarwady Division and south (Tanintharyi Division) and the east coast of India. This species is reported to occur mainly in brackish waters and historical records indicate that it can be found at the mouths of rivers. Leviton et al. (2003) provide a technical description of this species: Scales on thickest part of body with rounded or bluntly pointed tips, imbricate throughout; 5-7 maxillary teeth behind fangs; body elongate, ventrals distinct throughout, 300-338; 6-7 upper labials; 1 anterior temporal; 19-23 scale rows on neck, 29-37 on thickest part of body (increase from neck to midbody 8-14); young black with 35-55 bright yellow or whitish dorsal bars, posteriorly becoming complete bands that encircle body; head with curved yellow marking extending from snout to either side of parietal scales; adult markings become indistinct and older individuals are almost uniform grayish above, yellowish below. Total length: males 1190 mm, females 1200 mm; tail length: males 135 mm, females 110 mm.
