The ocean is only a serious problem if the car was driven on the beach, used to launch a boat from a trailer, or otherwise subjected directly to salt water, in which case the results will be quite obvious. I lived in Auckland New Zealand many years ago and there were plenty of 20+ year old cars around in a remarkable state of preservation. On some of the older British cars the salt air would cause a green haze on the chrome parts and dull the paint if the car was regularly parked a block or two from the water, but didn't seem to be a cause of serious rust. Road salt is the true enemy.

On the East coast the line of rusty or not falls somewhere in Virginia. North of it, beware.