Nothing. Rain comes from evaproation. If all you have to evaporate from is salt water then the evaporation leaves the water slightly saltier. Then the water vapor condensates, forms rain, and falls. What does if fall into? Salt water, making it slightly less salty. But either way you start with standing salt water and you end with standing salt water.
Excellent! Who said you didn't understand science?
But either way you start with standing salt water and you end with standing salt water.
But the Earth isn't covered with 8000 feet of salt water. At least not in my neighborhood.