Why is the ocean salty?

Question

askNib · Accepted Answer

Rivers pour into the ocean every single day. So why isn't the ocean fresh water, like the rivers feeding it? Rain falling on land is slightly acidic. As it trickles over rock, it dissolves tiny bits of minerals — including salts — out of the stone. Rivers carry those dissolved salts, drop by drop, all the way down to the sea. Every river on Earth is quietly delivering a little salt. Now the key trick: the sun evaporates ocean water into clouds — but only the pure water leaves. The salt stays behind, every time. That cycle has run for hundreds of millions of years. No salt ever leaves the sea, so it just keeps building up — that's why it's salty. The ocean is salty because rivers keep bringing in salt, and only the water ever leaves — the salt has nowhere else to go.