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.

[2] The species is native to Australia and New Guinea.

[3] The specific name, darwiniensis, refers to the city of Darwin, Northern Territory, Australia.

[4] The preferred natural habitats of H. darwiniensis are mangrove mudflats and seawater to a depth of 10 m (33 ft).