By 1983, the Hawaii Ironman was seven races old. ABC Sports and Sports Illustrated had discovered it. So had Budweiser—and soon, Timex would too. Despite growing corporate backing, Ironman was still seen more as amusing entertainment than serious competition.

That changed in 1984. For the first time, the field size topped 1,000, queries surpassed 10,000, and the race entry fee hit three digits: $100. As the day unfolded, one triathlete bested 50 minutes in the water, two went under five hours on the bike, and another finished with a sub-3-hour marathon and a sub-9-hour overall time—each setting records.

After the 1984 Hawaii Ironman, space-age technology began radically transforming bikes, top triathletes pushed for prize money, and never again would all previous winners compete together. Just like that, at the tick of the finish line’s clock, one era ended—and another began.