Why Is the Sea Saltier Than Rain?

Rain is water that has gone on a long trip to the sky and back, but while it was up there, it stayed very clean, like a fresh apple. The sea is salty because rivers act like tiny delivery trucks, constantly bringing salt from rocks into the ocean.

Imagine you have a bowl of plain water. If you sprinkle one pinch of salt, it might not taste different. But if you keep adding pinches every day for billions of years, that water becomes super salty! Rain starts as pure freshwater because when water evaporates from the sea to make clouds, the salt stays behind in the bowl. However, rain falls on land and runs over rocks. This running water dissolves tiny bits of minerals, especially salt, and carries them down into rivers. The rivers then dump all that dissolved salt into the ocean. Since the sun keeps evaporating water from the sea to make more rain, but leaves the salt behind, the ocean gets saltier over time!

Think of a steam cleaner cleaning a carpet. The dirty water is left behind while only pure steam rises up. That is what happens when ocean water turns into clouds. The evaporation process acts like a filter, letting only clean water vapor rise into the sky. When those clouds cool down and fall as rain, they bring back that same fresh water to the land. So, even though the sea has tons of salt trapped inside it, the water falling from the sky is essentially salt-free. It is not magic; it is just a simple cycle of evaporation pulling clean water up, while rivers keep pushing salty minerals down!