seawater
You know that ocean water is salty. How salty is it? What is the salinity of seawater? Average seawater is about 3.5% salt. The amount is different if there is a nearby source of freshwater. It is also different if there is a lot of evaporation in an area. How do you think these things affect seawater salinity? Seawater also contains other substances like sugars, acids, bases, and organic molecules.