Sea snakes prefer to live in shallow waters around continental shelves and islands, and are rarely found in open waters deeper than 100 meters. While some of them prefer to stay in mixed water on sandy or muddy bottoms, others prefer the clear water around coral reefs. Sea snakes dive at different depths, some deeper, some shallower. Sea snakes have been seen at depths of 40 to 50 meters. Shallow-water sea snakes generally dive for no more than 30 minutes, and stay at the surface for a very short time, each time just to show their heads, and soon take a breath and dive into the water again. Deep-water sea snakes stay at the surface longer, especially in the evening and at night. They can dive for up to two to three hours.

Sea snakes are selective about what they eat, and many have feeding habits related to their size. Some sea snakes have large, thick bodies with long, thin necks and surprisingly small heads, and such snakes feed almost exclusively on burrowing eel fronts. Some sea snakes feed on fish eggs, and these snakes have small teeth and small fangs and venom glands. Some sea snakes like to feed on fish with venomous spines, and in the Northern Sayan Sea of the Philippines, there is a sea snake that feeds exclusively on the eel-tailed catfish. Eel-tailed catfish have venomous spines that are so painful that they can seriously injure a person, but sea snakes don't care about that. In addition to fish, sea snakes also attack larger creatures.

During the reproductive season, sea snakes tend to gather together to form long snake formations that stretch for tens of kilometers, a large-scale gathering phenomenon that occurs when sea snakes are reproducing. Some harbors sometimes boil over as groups of sea snakes float to the surface. Completely aquatic sea snakes reproduce as ovoviviparous, giving birth to three to four 20-30 centimeter long baby sea snakes each time. Sea snakes that can come ashore, on the other hand, remain ovoviviparous, laying their eggs on seaside beaches and allowing them to hatch naturally.

Sea snakes also have natural enemies, sea eagles and other carnivorous seabirds eat sea snakes. They see sea snakes swimming in the sea, they swoop down from the air, pick up a far away, although the sea snake is fierce, but once it left the water there is no offensive ability, and almost completely unable to defend themselves. In addition, some sharks also feed on sea snakes. As for other natural enemies of sea snakes, at present do not know much.