I went scuba diving once in Acapulco. Some locals with an old sailboat rented out the equipment and gave a "training course" in this potentially dangerous sport. There I was, sitting on the gunwale in mask, fins and tank; when it was time for the lesson, the instructor said: "If you get in trouble, get my attention and make like you’re cutting your throat."
Well, about 25 feet down my mask began to press against my face, creating a vacuum that was popping my eyes out. Just before I panicked, I realized I was inhaling through my nose. I exhaled, and sure enough, the pressure equalized. I finished the dive unscathed, but I never did scuba again.
Now imagine the hundreds of marine biologists, archaeologists, geologists and botanists who work for the Smithsonian and need to get out of the office to do a little underwater fieldwork. It would not do to let these professorial types roam untutored in that beautiful but alien world.
Enter Michael Lang, the scientific diving officer for the entire Institution. Lang, a marine biologist himself, runs a rigorous entry-level science diving program for Smithsonian staff who have not been scuba diving before and need to do underwater research. He certifies about 180 scientists a year, many of whom are acquiring advanced underwater skills, such as the use of underwater cameras or learning to dive deeper for their research. There are at least 3,000 diving scientists across the country, according to the American Academy of Underwater Sciences. Lang’s basic three-week course includes safety procedures and the physics and physiology of diving, as well as actual instruction in diving. The Smithsonian trainees start out in a swimming pool, but before they are certified they will log 12 supervised ocean dives to qualify to work at a 30-foot depth. Divers can advance to depths of 60, 100, 130, 150 and, finally, 190 feet, which is the maximum depth for scientific diving.
"We’re not talking about a ten-minute course," Lang said. "You compare it with what you get at many resorts, where they throw you off the back of the boat after a few hours in the pool. It shows in accident stats. We don’t have any."
It’s not only for safety; it’s also a matter of time and money. "We want the scientists comfortable enough to jump into the water and focus on the science task," Lang said. "We also did a safety study on how many dives per day, how many consecutive days you can dive," he added. Because every day at sea is expensive, divers try for three to four dives a day. When a human body goes deep underwater, it absorbs nitrogen. When a diver returns to the surface, he exhales the stored nitrogen through his lungs. The process is called off-gassing, and if done too rapidly, it can result in the painful bends, a condition in which nitrogen bubbles lodge in the joints and sometimes the brain or spinal column, where they may prove fatal. To avoid the bends, trained divers rise at just 30 feet per minute, pausing for three to five minutes at 15 to 20 feet before surfacing.
"In fact," Lang explained, "at 190 feet, you only have two or three minutes at that maximum depth. You then begin ascending, stopping every few minutes and collecting more data on the way up."
Most dives are less than 100 feet, and the majority are 60 feet or shallower. "A lot of our diving is coral reef work; and corals don’t grow very deep because of their symbiotic relationship with algae that need sunlight," he said.
When research requires very deep dives, say 3,000 feet, as it did when the 3-D IMAX film Galapagos was produced for the Smithsonian two years ago, the descent is made in a submersible, which has a mechanical arm and suction tube for gathering specimens. Lang was on hand for the filming in the Galápagos Islands with a team of about 25 divers, for the more shallow work at about 130 feet.
One of the main problems, Lang said, was handling the huge and ungainly IMAX camera. In its aluminum casing, it resembles a mini-submarine. The camera unit weighed 1,200 pounds out of the water and required three divers to steady and operate it.