The Iranian threat, of course, is real, but its immediacy gets turned on and off by the Prime Minister like a faucet. In this tube the coals were placed, and when the water in the urn was hot, it could be drawn off by means of a faucet at the side. The drip-drip of water from the faucet sounded loud in the quiet.
After multiple dives per day or multiple days of diving, a minimum surface interval of 18 hours is recommended. If you had to do a decompression stop during a dive, the recommended time to wait before flying is a bit more of a gray area.
How long you can stay under. It depends on a number of variables, such as, are you diving with air or a mixed gas like nitrox. Other considerations include water temperature, how deep you are, are you making a repetitive dive, etc. Diving to 60 feet using Nitrox 32, your NDL would be 100 minutes.