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.
Ocean water is full of life. It is teaming with both botanical and zoological particles, waste, sperm/eggs, and an incredible number of micro organisms.
One single litre of sea water can contain up to 20,000 different species. Now before that grosses you out, know that every surface, including the air we breath, is also carrying life around that we don't see, but ingest just the same regularly.
Seawater contains sodium certainly, but it also contains trace amounts of chloride, magnesium, sulfate and calcium (this is good stuff). Small amounts of other substances are found, including amino acids at concentrations of up to 2 micrograms of nitrogen atoms per liter. But as was mentioned, be very careful as many recreational and commercial boaters dump waste intentionally or unbeknownst to them.
Also, NEVER use water near a farm. All farms use extreme amounts of pesticides/herbicides/fungicides/chemical fertilizers. Many test studies in farm areas near oceans have shown high levels of cancer directly related to agriculture chemical run off into water that people are fishing and swiming in.
Cooking or boiling sea water with it's chemical and organic composition will add smell and it's own flavor to the pasta. This may or may not be good.