Aortic atherosclerosis is a condition in which plaque builds up in the inner lining of the aortic artery. This condition can cause many symptoms and result in surgery. This article discusses what causes aortic atherosclerosis, symptoms and treatments.
An average scuba diver can stay underwater for 45 to 60 minutes on a 40-foot dive. Many factors affect tank duration, including depth, tank volume, and the diver's air consumption rate.
With this, seals can in all reality stay underwater for approximately 4 days from what I've read. I'm sure the exact time for their equipment is highly classified material. But as to the original question, would seals have to stay underwater. Most seal approaches are done under cover of nightfall to increase stealth.