Saltiest means having the most salt in it.
The word saltiest makes people think of strong flavors and sometimes of not being healthy.
Examples:
This soup is the saltiest I've ever tasted.
The ocean water is the saltiest near the equator.
I don't like the saltiest chips.
The saltiest food in the world is too salty for me.
The saltiest sea in the world is so salty that nothing can live in it.
The saltiest snack in the world is a challenge to eat.