The 35-year-old Hungarian has three individual Olympic Games gold medals and nine individual World Championship gold medals in long course. The highlight of her career came at the Olympic Games in Rio de Janeiro 2016 when she took three gold medals and one silver.
The nickname "Iron Lady" comes from her often hectic competition schedule, where she has competed in several different distances and strokes.
Her greatest achievements have come in medley, but Hosszú has also taken championship medals in backstroke, butterfly, and freestyle.
"For 30 years, the water has been my home, a refuge where I have found comfort and strength", writes Katinka Hosszú on Instagram.
She made her Olympic Games debut at the age of 15 in 2004 and participated in a total of five Olympic Games. Only two women – Sarah Sjöström and Katie Ledecky – have collected more individual World Championship medals in long course.
Katinka Hosszú is also still the world record holder on 200 meters medley.
"Already the first time I stepped into the pool as a child, I understood that I had found something magical. The water's cool embrace was like finding home, a place where gravity ceased and where every stroke took me closer to my dreams", writes Hosszú.