Where does the salt come from in the oceans?
The 'salt' comes from weathering and erosion-of the earth's crust, of mountains...and from being transported by rivers and streams. Fresh water from those rivers don't significantly dilute seawater, because they also carry miners...and the sun evaporates some of the water from the oceans, transforming it in water vapor, the gas form of water...leaving salts behind. Keep in mind that 'salt' is a broad reference for various forms of minerals that are suspended in sea water. An interesting fact...if all the salt from the oceans was spread on land, it would leave a layer 500 feet thick!