The aquatic ambassador: to bring nations together, Lynne Cox swims across troubled waters.

Last October, Lynne Cox swam around the Gulf of 'Aqaba, a slender tongue of water that extends inland from the Red Sea and is shared uneasily by three nations: Israel, Egypt, and Jordan. The swim was designed to call attention to, and gain support for, peace efforts among these nations.

Cox, 38, is one of the greatest endurance swimmers in the world. Her resume is comprehensive: a 12 1/2-hour crossing from Catalina Island to the California coast at the age of 14; an English Channel record at 15; a 20-mile (32.2 km) swim across New Zealand's Cook Strait (which she was the first woman to achieve) at 17; a swim across the Strait of Magellan in 44 [degrees] F (6.7 [degrees] C) water at 19. In short, Cox has swum across some of Earth's most treacherous bodies of water.

One of Cox's feats stands out from others of its kind: her crossing of the Bering Strait from the U.S. to the Soviet Union in 1987. On that occasion Cox, protected by neither a wet suit nor insulating grease, swarm for more than two hours in water that ranged from 38 [degrees] F to 44 [degrees] F (3.3 [degrees] C to 6.7 [degrees] C), temperatures that few humans could survive beyond 30 minutes.

The Bering swim was remarkable for political as well as physiological reasons. The waters between Siberia and Alaska had been closed since 1948, and it took Cox 11 years of patient but persistent diplomacy to achieve her dream. Thus, when in early August 1987 Cox emerged on the Soviet shore blue-tinged and shivering and fell into the arms of Inuit well-wishers, she could boast of being the first person to have crossed those water - in or out of a ship - in nearly 40 years.

The historic impact of this feat was recognized at the highest level when Mikhail Gorbachev, then leader of the Soviet Union, said, "It took one brave American by the name of Lynne Cox just two hours to swim from one of our countries to the other. She proved by her courage how closely to each other our peoples live."

SWIM FOR MID-EAST PEACE

Before her Gulf of 'Aqaba swim, Cox spoke of the challenge ahead. "I've been training all along, but the training has been mostly in the gym," she said. "Now I'm really increasing the water time, and I'll do a couple of four-hour swims in the ocean.

"I'm going into desert water," Cox added matter-of-factly. "I've heard a variety of temperatures - between the high 70s and mid-80s [degrees Fahrenheit]. I'm planning to stop every half-hour to drink lots of fluids. And I'm going to wear a light-colored bathing suit [to reflect heat away from my body]."

I suggested a yellow suit - light-colored but also highly visible. "Well, maybe," Cox replied in her lilting voice. "But the problem with yellow is that, at least off Florida, they found that sharks are most attracted to that color. Yellow is called yummy yellow."

BUILT FOR WATER

Dangerous marine animals aside, the [Gulf of 'Aqaba] swim was among Cox's most physically challenging. A battery of scientific studies done on Cox over the years has revealed some startling facts about her physiology. First, the muscle and fat in her body are so perfectly balanced that she has neutral buoyancy, meaning that she neither sinks in water nor floats. As one researcher told her, "You're at one with the water" - a critical energy-saving advantage during long-distance swims.

More remarkable, however, was the discovery that Cox's body is superbly adapted to cold temperatures. On entering cold water, a person's surface blood vessels constrict, forcing warm blood to the vital organs at the body's core. Normally, however, this is a stopgap that works for only a short time. By contrast, Cox's vital organs are insulated by an evenly distributed layer of insulating fat. Warm blood shunted to her core remains warm dramatically longer. So effective is this "internal wet suit," that Cox's temperature actually rises during a hard swim in cold water.

In the warm water of the Gulf of 'Aqaba, then, Cox was in danger of overheating. She had to draw on the deep reserves of determination that have seen her through the trickiest moments of her most dangerous swims: the attentions of a shark off the Cape of Good Hope; becoming lost in fog in the Catalina Channel; the warning numbness she felt as the Soviet landfall came in sight at the end of her Bering [Strait] swim.

"When I'm swimming," she says, "I think a lot about the physical realities around me: Where am I in relationship to the boat? I think about my stroke. I think about what it's taken to get to that point - that's a real motivator."

NATIONS UNITE

From Egypt to Israel; from Israel to Jordan. Cox's swim along the Gulf of 'Aqaba covered approximately 15 miles (24.15 km). "Basically the idea was to celebrate the peace process that began between Egypt and Israel and has now continued between Israel and Jordan - I literally and symbolically traced the route the process followed. Some borders have now been opened. By swimming from one national boundary to another, I hoped to push the borders open a little further."