The ocean water is salty. This is because they primarily comes from rocks on land and openings in the sea floor. Rocks on lands are the major source of salts dissolved in sea water. Rainwater falls on that rocks results the acidity and erosion of rock surfaces. This release ions that are carried away from streams. Many of them are removed from the water but others don't get removed easily. Their concentration increases time to time. 
Also Read :- What is an ocean?