Hydrophiinae, also known as sea snakes, is a group of venomous

Venomous snake

"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom...

 elapid

Elapidae

Elapidae is a family of venomous snakes found in tropical and subtropical regions around the world, terrestrially in Asia, Australia, Africa, North America and South America and aquatically in the Pacific and Indian Oceans...

 snakes that inhabit marine environments for most or all of their lives. Though they evolved from terrestrial ancestors, most are extensively adapted to a fully aquatic life and are unable to move on land, except for the genus Laticauda

Laticauda

Laticauda is a genus of snakes from the family Hydrophiidae. Laticauda are the least adapted to sea life of all the members of Hydrophiidae; they retain the wide ventral scales typical of terrestrial snakes and have only a poorly developed tail fin...

, which retain ancestral characteristics, allowing limited land movement. They are found in warm coastal waters from the Indian Ocean

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 to the Pacific.

All have paddle-like tails and many have laterally compressed bodies that give them an eel

Eel

Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...

-like appearance.