Explain how sea snakes that do not lay their eggs on land reproduce

Sea snakes are ovoviviparous (development of eggs that remain within the mother's body up until they hatch or are about to hatch.). The young are born alive in the water where they live out their entire life cycle.

Explanation:

Mating in sea snakes takes place under water.The male sea snakes have two penises but only one is used.During mating the sea snakes must surface for air hence the female controls breathing for she swims to the surface and pulls the male along attached through the hemipenis which is used by the male snake during mating.The sea snakes develop eggs inside their body and end up giving birth to live young ones which means babies are born live in the water.In snakes there is no parental protection so when  baby snakes are born live they are completely on their own.The snakes are born with fangs and venom and they can inflict a deadly bite. This type of reproduction is known as ovoviviparous.