Many people panic the first time they are hooked up to an underwater breathing machine; to inhale below the chop of the waves feels like the pinnacle of self-destruction, and sometimes, it is. The rush of adrenaline can cause novice scuba divers to blow through a whole tank of gas in what feels like minutes, sucking down breath after unassured breath. The deeper you are, the faster the tank empties: at 30 meters, the pressure is equivalent to four of earth’s atmospheres and you need four times the air to fill your lungs. For every 10 meters, add the weight of another sky. (read more...)