When describing salt water, which part is the solution?

The solution is the whole thing. A solution is a mixture of substances. In this case, salt is mixed with water to make a solution.

Salty water is a broad spectrum. There are different types of salt water. There is braking water, which is a mixture of both freshwater and saltwater, and there is salt water measured in PPT, or parts per thousand.

Abay where the river empties into the sea