The crab-eating water snake, or white-bellied mangrove snake as it is called in Australia, confines itself mainly to tidal habitats, where it preys on small fish and crabs. In particular it is locally common in mangroves.

There are several colour variations ranging from brown or grey with black spots, to purplish-black. The belly is pale in colour. The jaw is recessed under the head, and the eyes positioned towards the top of the head.

It is wide-ranging from India, Bangladesh, Myanmar and Thailand down through the Malay Peninsula through all the larger islands of Indonesia. In the extreme east of its range it is found in New Guinea and northern Australia.