The greatest swimmer of all time.Wait. That's not nearly going far enough.The greatest Olympian of all time.Hold on. We can go further, can't we?The greatest athlete of all time. Yes. That's more like it. The greatest athlete who has ever lived. The best ever.You certainly can make a strong claim that Michael Phelps is the greatest athlete we've ever seen.More dominant than Gretzky. More special than Jordan. A bigger deal than the Babe.Even before he jumped into the pool at the Rio Olympics, the American swimmer was already a legend, already the most decorated Olympic athlete in history. Then he took his dominance to new heights. He played in the Rio water as if he was splashing around in his backyard pool.Phelps has won more gold medals (23) than some countries. NBC Olympic commentator and former swimming star Rowdy Gaines said he used to think he was a "big deal.""And I won three gold medals," the Winter Haven native said on the air.Three? Sounds like a weekend of work for Phelps. Remember when you were a kid and you would throw objects to the bottom of the pool, then dive in to retrieve them? Yeah, Phelps does the same thing. Except he comes up with Olympic medals.So what about this idea that he deserves to have his name right alongside the all-time greatest athletes?He has never been hit while swimming, like Jim Brown or Jerry Rice was hit. He has never had to guard anyone, like Jordan or Magic or LeBron. He has never had to compete in the most popular sport in the world, like Pele or Messi.Practically everyone knows how to swim, but can everyone hit a baseball? Even puppies can stay afloat in a pool, but most people would break a bone trying to ice skate while being chased by toothless hockey players who look like Transformers.Some might even argue that swimming isn't even the most difficult sport contested in a pool. After all, water polo looks like a combination of swimming, wrestling, dodgeball and mixed martial arts.Doesn't matter. Jump in a pool and swim as hard as you can for two minutes, then suggest that swimming isn't a real sport.Other athletes, such as Muhammad Ali, Jackie Robinson and Jesse Owens, have had a greater social impact than Phelps. Other athletes, such as Pele and Jordan, have been more popular. Many, such as Tiger Woods and Tom Brady, have made more money and been on more Sports Illustrated covers.Phelps' checkered out-of-pool exploits — a 2009 photo of him smoking from a bong and a 2014 DUI arrest — along with his perceived arrogant attitude have made him a complicated figure, practically perfect in the pool, yet flawed outside it. He has never been as embraceable as many of our Olympic stars. We've never thought of him like we do Mary Lou Retton or Mark Spitz.But because of Phelps' complete domination of the sport, he deserves to at least be in the conversation as the greatest athlete ever.What puts Phelps in a category few can match is how long he has been this good. How many athletes can claim a 16-year stranglehold on their sport? For most of his lengthy career, not only has Phelps been good, he has been the best.One event encompasses Phelps' career perfectly: The 200-meter individual medley. It's a race that requires speed, endurance and all four swimming strokes: freestyle, butterfly, breaststroke and backstroke. It's the ultimate test of a swimmer.And Phelps has won gold in the event in four straight Olympics. Think about that. Four Olympics. Twelve years.He won gold for the first time as a teenager, just 19 when he set the Olympic record in that event in 2004. He won his fourth in the event Thursday night as a 31-year-old, beating his closest competitor by nearly two seconds. Two seconds is like winning the Super Bowl by four touchdowns. A blowout.In between, he was a beast, setting the world record eight times. With Phelps almost too good to be true, the only explanation some have for his dominance is that he must be cheating. But all this guy does is this latest craze of cupping, which looks like it does more harm than good. But now everyone is going to do it because Phelps does.Every four years, we turn on our televisions and see the same thing. Phelps jumps in a pool, crushes his opponents, crawls out like he just got hit by a truck, gets his gold medal and then jumps back in the pool for another event.Rinse, repeat. Night after night, Olympics after Olympics.Each Games has meant a new set of challenges and another round of rivals. The Washington Post figures that if Phelps never had competed in individual swimming events, as many as 27 swimmers would have seen their Olympic overall medal and gold-medal totals increase.The competition has changed. The locations have changed. Phelps has changed.But the results have stayed the same. Phelps wins time and time again. He's a freak. He's 31 and looks like he's in his prime. He might even be in his prime. Would you be shocked if he came back in four years and added even more gold medals to his pile?Not that he needs to. He's already the best swimmer who has ever lived. The best Olympian, too.And, yep, I'd even go even further than that.