He's the most decorated Olympian of all time and one of the greatest (if not the greatest) swimmers that the world has ever seen - but what about his taste in music?
All throughout his career, Michael Phelps has been seen wearing his trademark headphones right before a race, to block out external noise and get himself in the zone.
But what about his playlist for this year's Olympics?
In a Facebook Live chat with People, Phelps revealed that old school Eminem (circa 2003/2004) was a favourite to get himself pumped up, as well as EDM hits 'Promises' by Nero, and an unnamed song by Skrillex.
'No Beef' by Afrojack and Steve Aoki was also in the mix.
He said: "I was just trying to really get going and really get amped right before I would walk out and [the music] helped a lot – I was sometimes tired."
Hear all of those songs below - and now you know the playlist to reach for the next time you go for a dip.