Michael Phelps
Michael Phelps might be the greatest athlete of all time. Pictured: Phelps speaks during a press conference at the Main Press Centre on Aug. 14, 2016 in Rio de Janeiro, Brazil. Jamie Squire/Getty Images)

Now that Michael Phelps is officially retired with seemingly little chance of changing his mind, it might be time to try and put the Olympian’s career into perspective. The swimmer has called it quits after a career unlike any athlete in history.

Is Michael Phelps the greatest athlete of all time?

It might be an impossible question to answer, but there’s no doubt that Phelps is in the conversation, given everything he’s accomplished. Phelps is the most-decorated athlete to ever compete in the Olympic Games, and even he is taken aback at what he was able to do on the world’s grandest stage.

“I think it’s kind of cool to be able to look back at a long career that I was able to have,” Phelps told International Business Times while promoting Colgate’s campaign to save water. “I can honestly say everything I put my mind to, I was able to accomplish. It started out wanting to win one Olympic medal. Looking back, I think it’s still hard to fathom the amount of medals that I was able to win at the Olympics. Obviously, it was just through hard work and never giving up. It’s wild to think about. I don’t know when it will sink in, but I’m looking forward to that time.”

There’s certainly no question that Phelps is the greatest Olympian ever.

Phelps is the all-time leader with 28 total medals. Gymnast Larisa Latynina is a distant second with 18 total medals, and Phelps has more than two times as many medals as any American that’s ever competed in the Games.

With 23 gold medals to his name, Phelps has an even bigger lead on Latynina. The former Soviet gymnast is tied for second all-time with nine gold medals, along with the likes of Mark Spitz, Carl Lewis and Usain Bolt.

It isn’t just Phelps’ dominance that puts him in the GOAT conversation. It’s the fact that he was so good for so long. Even though he didn’t win a medal in the 2000 Olympics, he qualified to compete in Sydney, Australia at just 15 years old. Phelps went on to prove he was the greatest swimmer in the world over the next four Olympics, winning at least four gold medals in each Olympics over a 12-years period.

Has any player in any sport unquestionably been the best for that long?

LeBron James has been the NBA’s top player for the last decade, but he probably won’t go down as the greatest basketball player in history. That honor belongs to Michael Jordan, and his dominance in the 1990s included a two-year retirement.

There’s probably no more clearly defined GOAT in any team sport than Wayne Gretzky. The greatest hockey player of all time had a 21-year career in which he led the NHL in points 11 times.

It’s been incredible to watch Roger Federer win Grand Slams over the span of 14 years, but his reign as the world’s No.1 player didn’t last 12 years. Tiger Woods was dominant from the time he won his first major in 1997 until his last in 2008, though he still ranks behind Jack Nicklaus when it comes to being the best golfer in history.

Of course, comparing an Olympic athlete to someone that competes in a sport with yearly seasons is difficult. Phelps is only now starting to fully appreciate his career.

“I’m basically kind of working back through my career now, year by year, to just realize what has occurred for most of my life, and it’s pretty wild. It’s pretty crazy to think about, but it’s awesome. It just shows you that if you’re passionate about something and you want something bad enough that nothing can stand in your way,” Phelps told IBT.

“I did one swim meet and would go right to the next, or I would go right back into training. So I never really had time to sit back and understand or appreciate what was going on. I think (about it) now, being able to have a little bit of free time to go back and kind of relive some of the moments that I had and some of the memories that I had throughout my career. But I think it’s gonna be an ongoing thing that’s a process for years and years to come until I’m ready to understand everything that I went through.”