Ocean water is not drinkable by humans unless it goes through an expensive and time consuming cleaning and treatment of the salt process.
The high salt content in the ocean water is deadly to humans so humans should not drink any ocean water.
However it's unlikely that you would die if you happened to accidentally swallowed a bit of ocean water when swimming.
But do not drink glasses of the ocean water because the salt content is too high for humans to digest without serious illness.
There are ways to treat ocean water to make it drinkable but it's very costly and usually not worth it unless you need that water for drinking.