What are salinity gradients?

Salinity gradients are like differences in how salty different parts of water are, kind of like when one part of your bathwater is super salty and another part feels just right.

Imagine you're playing with a toy boat in the bathtub. If you add salt to one side of the tub but not the other, the boat might start moving from the less salty side to the saltier side, that's because water wants to balance things out!

When there’s more salt in one area than another, water moves from where there’s less salt to where there’s more salt. It’s like when you put a drop of food coloring into still water, the color slowly spreads out until it’s even.

This movement happens all over the ocean too! In places where fresh water meets salty sea water, like near river mouths, salinity gradients help shape currents and can even affect how fish swim around. It's just like your bathtub, but much bigger and more interesting!