He's the first male to make 5 Olympic teams. He has world records and American records. He's the most decorated Olympian of all time with 22 medals. His records speaks for itself. There aren't many who can claim to have achieved the same level of success in swimming, and I doubt there will be many if any others who can do the same. He may not be finished yet and may go on to win more in Rio 2016.
Michael Phelps is the winningest Olympic swimmer of all time, and continues to show off his skills. He has qualified for the fifth time to compete at the Olympic games this year. He has shown that his hard work and commitment has propelled him to be the greatest swimmer we have seen.
Yes, Michael Phelps is probably the greatest Olympic swimmer ever. He has the most medals of any Olympic swimmer in history. This fact alone makes him one of the greatest if not the greatest Olympic swimmer of all time. Furthermore, he has longevity see as though he has been in a number of Olympic competitions.
Michael Phelps has already made Olympics history by being the first U.S. men's swimmer to qualify for five games. Phelps has always performed well as an Olympic swimmer in previous games. He has won numerous gold medals already and will likely win more in the Rio games. Therefore, many do believe that Michael Phelps is the greatest Olympic swimmer ever.