The real renaissance of Catalina Channel swimming did not occur, however, until the 1970s. That's when a tiny swimmer from Pomona College, Penny Lee Dean, set the all-time standard for men and women, crossing from Palos Verdes to Doctor's Cove near the western end of the island in just under 7 hours and 16 minutes.
Cox, now 48 and living in Los Alamitos, recalls that ironically it was Cox's failure to cross the Catalina Channel that drove her as much as her many successes.
She was 17 and trying to set another record -- having already mastered the English Channel twice, both in record times. On her way from Catalina to the mainland that September night in 1974, however, nature shook any notion that Cox or any other top swimmer could assume dominion on what was still the open ocean.
A fog descended so heavily it cut visibility to half the length of a kayak. Two escort boats that ventured just slightly ahead lost Cox. And for several panicked minutes she treaded water. Alone. She recalled feeling some unknown creatures wriggling past her sides and beneath her in the inky water. Bonita? Seals? Blue sharks?
"And it's pitch black all around you," she recalls. "Everything is magnified."
By the time her support crews found her, Cox's nerves had been stripped bare. She grabbed hold of a paddle board, assistance that officially put an end to her swim.
But, just weeks later, with the support of her parents and a swimming mentor, she returned to the Channel. This time -- swimming mainland to island -- she not only finished but set another record.
"If I had stopped then, all this training and all this effort would have been for naught," Cox says. "I never would have gone on and swum the Bering Strait, the Cook Strait [between the north and south islands of New Zealand], the strait of Magellan and on and on and on.
"There are days when it is just not right. There are days when nature is just stronger than you are," Cox says. "But that is part of the beauty of it. You sort of have to work through those big things and decide whether it's really important to you or not."