You may not know that when the ocean was first formed, the sea water was not as salty as it is now. It gradually became salty later. In the early days of the earth's formation, large amounts of water vapor were continuously released from the earth's interior. This water vapor condenses into rain when it is cold in the sky and falls on the surface, forming turbulent surface runoff. They pass through thousands of mountains and valleys and gather into primitive depressions, forming a primitive ocean. At that time, the salt content in seawater was far less than it is now.
However, during the long evolution of the earth, the scene of seawater evaporation-precipitation-reevaporation-and precipitation has been constantly staged on the earth. Surface runoff formed by atmospheric precipitation washes the land again and again, bringing large amounts of salt from the land rocks into the ocean. Over time, year after year, the salt content in seawater continues to increase, and the original fresh water gradually turns into salt water.
It is also believed that some of the salt in seawater is released to the surface from deep in the earth's crust in the form of gas. For example, when volcanoes in Italy and Iceland erupt, sodium chloride vapor in the emitted gas accounted for 50.29% to 76.01% of all sublimated substances. The large amount of salt contained in these vapors will also enter the vast ocean through various channels after being sprayed out of the surface.