Back in the days of the TV show Sea Hunt, Mike Nelson's biggest concern was running out of air. Today scuba divers wonder whether they should even be breathing the stuff. Some of them aren't.
The last time Ed Soellner went diving, he chose to breathe something other than air—something he hoped would ensure against decompression illness, or the crippling malady called the bends. But instead of being "bent," he wound up dead.
Soellner drowned on July 5, 1992, apparently after suffering a seizure while he was exploring a shipwreck off the New Jersey coast. The convulsion was most likely caused by the high oxygen content of the gas he was breathing—a blend called enriched air, or nitrox. Soellner, an accomplished diver who was 33 when he died, was one of four who lost their lives in 1992 while breathing gases other than air.
Underwater, ordinary compressed air has a number of disadvantages—including a contributing role in the bends. Under pressure, a diver's body absorbs nitrogen from the gas in his or her tank. This is usually harmless, but under certain circumstances the nitrogen can form bubbles in the body as the diver ascends. If these bubbles lodge in the joints and elsewhere, they wreak havoc with nerve function and blood flow.
Another problem with nitrogen is its tendency to cause narcosis, a.k.a. "rapture of the deep," an effect that is the equivalent to standing up quickly after drinking a pitcher of margaritas. A diver suffering from narcosis may become disoriented and fail to keep track of his air supply or the location of his dive boat.
Seven or eight years ago a handful of scuba divers began diluting the air in their tanks with additional oxygen, assuming that less nitrogen in one's mix would mean safer dives. The idea wasn't new—commercial and military divers had been using enriched air for years—but it was an innovation for people who weren't being paid to dive. Enriched air does offer some advantages. It can give a diver more time on the bottom or lessen the chances of decompression problems, and it may be particularly useful for older divers, who seem to be more prone to the bends.
"Any time I'm diving shallower than 130 feet, I use enriched air," says Evelyn Bartram Dudas, 48, of West Chester, Pa. She became certified in its use in 1991. A veteran diver, Dudas was paralyzed temporarily in 1968 following an air dive to 165 feet. Until she started using enriched air, she suffered skin bends, which can appear as a rash or blotches, "about every third day of diving."
"I'm not sure that it will replace air, but it certainly has a place in recreational diving," says Joe Clark, 53, a co-owner of Ocean Divers in Key Largo, Fla. In 1988 Clark became the first dive operator to offer enriched air to recreational divers. "It's good for people my age who like to dive a lot. If you don't use it to stay down longer, you have a built-in safety factor."
The trade-off is the potential for oxygen toxicity. Oxygen is vital to life, but in high concentrations it becomes a poison, causing nausea, vision problems, irritability, even convulsions. Furthermore, an individual's reaction will vary depending on the length of time spent underwater, one's depth, the percentage of oxygen in the mix and one's body chemistry on a given day.
An analysis of the gas Soellner was breathing when he died showed it had a higher percentage of oxygen than experts would recommend for the depth and duration of a dive such as his. Proponents of enriched air say they were saddened but not surprised by Soellner's death.
Another incident, one that took place earlier the same week at the Devil's Eye cave system in north-central Florida, was more troublesome. James Fernandez, 28, of Deerfield Beach, Fla., went into convulsions, blacked out and drowned while breathing enriched air and swimming against a current. Although Fernandez's oxygen levels weren't considered extremely high, the added exertion of fighting the current may have pushed him over the edge. That same month a third diver survived an oxygen convulsion while diving in a North Carolina lake.
Two more divers died in 1992 while breathing yet another gas, tri-mix, which adds helium to the recipe, but the mixture itself was not to blame. One diver who was using it ran out on the bottom, and the other let go of a guideline and became lost inside a wreck.
The circumstances of each of these accidents varied, but the divers all had one thing in common. All were part of a small but increasingly visible group of divers—amateurs only in the true sense of the word—who have looked for new challenges in what until recently was the realm of the pros.
"From the moment Jacques Cousteau put a regulator in his mouth, diving has been high tech," says Richard Nordstrom, a diver since 1961 and the CEO of Cis-Lunar Development Laboratories, Inc. in Chadds Ford, Pa., which is preparing to market an advanced rebreather that will enable recreational divers to recycle the air in their tanks and remain underwater for many hours. "A lot of serious divers are dreamers. They're always looking for better ways to do things."
Dive technology may be moving too fast to suit some, particularly after all the accidents in the summer of '92. But the mainstream has always been slow to accept newfangled gadgets, says Nordstrom. "I remember the first time I saw a BC," he says, referring to an inflatable buoyancy compensator—a vest inflated with gas to provide buoyancy—worn by a diver who drowned because he carried more weight than the device could lift. "Some official saw the guy and said, 'That's why he died. He was wearing that thing.' "
A buoyancy compensator is now standard safety equipment for all divers. In the early 1970s divers used mathematical calculations, experience and their best guesses to determine how much air they had in their tanks. Today no one gets wet without a submersible pressure gauge, which indicates how much gas remains in a diver's tank, and many divers use small computers to determine depth and the length of time they may spend on the bottom. And while this summer there were no underwater fatalities attributable to enriched air, whether it will be a standard breathing mix in the future remains to be seen. Of an estimated three million to 3.5 million active divers in the U.S., only 10,000 or so are certified to use enriched air, and probably fewer than 500 are certified to use tri-mix.
"Nobody's going to confuse a day hike in Yosemite with trying to reach the top of K2," says Karl Shreeves, manager of technical development for the Professional Association of Diving Instructors (PADI), the largest certifying agency in the sport. To date, PADI has chosen not to become involved in teaching the use of enriched air to recreational divers.
"But just because it isn't suitable now doesn't mean it won't be in 15 years," Shreeves says. "Jump ahead 15 years. Suppose we have electronic closed-circuit rebreather systems that are as easy to use as present open-circuit scuba. Logic dictates that they will become recreational."
In 15 years it is likely that scuba diving will have undergone some interesting changes—not entirely unimagined. Fifty years from now, when the sport celebrates its centennial, it's hard to fathom what technologies might exist. And yet no matter how far the technologies advance, a small group of pioneers will always follow in Cousteau's finsteps, extending the horizons underwater. Some will not return.
Cis-Lunar's rebreather lets Nordstrom spend more time with an aquarium-dwelling turtle.
PETER E. HESS
Dudas (top) favors nitrox; Bill Stone's high-tech MK-4R rebreather is strictly for pros.
[See caption above.]
Cathie Cush lives in Newtown, Pa., and writes often about scuba diving.