Hydrelaps is a monotypic genus of venomous sea snake in the family Elapidae. The genus contains the sole species Hydrelaps darwiniensis, also commonly known as the black-ringed mangrove snake, the black-ringed sea snake, Darwin's sea snake, and the Port Darwin sea snake. The species is native to Australia and New Guinea.
The specific name, darwiniensis, refers to the city of Darwin, Northern Territory, Australia.
The preferred natural habitats of H. darwiniensis are mangrove mudflats and seawater to a depth of 10 m (33 ft).
H. darwiniensis is viviparous.
