It is said, that the water you use to cook pasta should be as salty as ocean water. So can I simply use ocean water to cook my pasta without adding salt to it?
You certainly can. There are a few things to consider before popping down to the beach and grabbing a bucket.
Some areas of the sea are highly contaminated with toxins. Look for some sort of signage to give you a hint, OR look for fishermen. If they feel safe with the fish they are catching I'd be inclined to think the water was also fine.
Sea water is, as you know, very VERY salty. On average around 35g per Liter. So you may benefit from using half tap and half sea water.
Be sure to boil the water for a few minutes before adding any food, just to be sure any harmful "biological organisms that might contaminate the water".
Another consideration, you may be interested in, would be harvesting your own salt from the sea water. That way you have more control over the amount penetrating your food/blood stream.