Johnstone, the oldest swimmer to compete at this 15th Masters Worlds edition, soon created a sensation at the Parc Jean-Drapeau pool: after each of her swims, fellow swimmers from all over the world, in awe of such determination, would congratulate her and ask for a picture with her. Truly an inspiration for all, Johnstone played along, amused by her sudden popularity.
"I'm so happy to be in the sport of swimming, I don't know how to stop," she said with a laugh.
"I was ready to fly from hometown Auckland to come here. Swimming keeps me young and healthy!"
Johnstone paused for a few seconds, and said, weighing her words: "Underneath the wall of my body, I feel thrilled to help youngsters and adults to swim or keep on swimming."
Johnstone was four when she first dipped a toe in a swimming pool and was very competitive from an early age. Aside from swimming, she played various sports like field hockey and tennis.
Katherine Johnstone (NZL) after her 200m freestyle effort - credit: Delphine Schmutz/FINA
Johnstone first took part in a FINA World Masters meet in Christchurch, New Zealand in 2002. She then travelled to Perth, Australia in 2008 and to Riccione, Italy in 2012.
"Here, I see old friends that I met at previous Masters Worlds, it's fantastic," she said.
Johnstone trains twice a week at Auckland's North Shore Masters club. "My coach has become my best friend," she said.
"Until my body allows me to, I'll keep going."