< April 14 2005. We descend 94 feet below the surface of the water 1/2 mile offshore the western side of Oahu, Hawaii. We faced the rusted barnacle covered bow of the Mahi, a 184 ft sunken Navy ship, sunk in 1982 as an artificial reef project. On the ocean floor lies a plaque “In remembrance of Bruce”. Bruce was a long time diver of this area who died taking his last breath from the same kind of tank we now carried on our backs. This was my twelfth logged dive, Marty’s 20th. After taking a shot of the plaque with his new Nikonus underwater camera, Marty took a photo of an eel hidden in a rock nearby. It was already time to ascend to the top of the ship.
It is always difficult to stay down at that depth for long. Air is condensed; there is a lot of pressure down there. It's the weight of all the water--and air--above you. At the surface of the water, a column of air stretches hundreds of miles out into space. When underwater, however, add the weight of the water to the atmospheric pressure. A 10-meter (33-foot) column of water weighs 14.7 pounds per square inch, so at a depth of 10 meters, the pressure is two atmospheres: half from the water and half from the air above it. Pressure also influences how divers use air. At ten meters, for example, the increased pressure means your lungs hold twice as much air as they do at the surface--and a diver breathes the air in the tank twice as fast. The deeper we dive, the more quickly we use up the air in our tanks. At 30 ft Marty took more photos and went to change to his brand new wide angle lens. It was missing he conveyed to me in a sort of make shift sign language mixed with frustration and panic. I followed him as he again descended to the ocean floor and we both looked around for the lens. Then I looked at his air. It was getting in the red zone already and we still had to ascend and make our decompression stop. After informing the others we were going up we went to the rope and started our ascent. Marty had to reach for my extra regulator and share my air. My air supply was in the red now also. He held me back as he timed our 3 minute stop at 15 feet down. The longer we stayed down and the deeper we went, the more nitrogen dissolved into the body tissues. If we ascend too rapidly, the dissolved nitrogen comes out of solution too quickly and forms bubbles in the tissues. We would get “the bends”: severe pain (particularly in joints), dizziness, blindness, paralysis, and convulsions. I looked at Marty and thought: “So this is how we die”. He let go and I sucked in a few last breaths kicking hard for the top letting my air out as slow as I dare. We made it to the surface, safe with both tanks empty and no bends. I breathed in the unchambered, free air we take for granted daily with a sigh of relief.