What is harder: swimming for 72 hours in the open water or swimming for 72 hours in a pool?
The debate can go either way. The open water can be cold and rough. But you can also just swim, straight navigating off your escort boat. In contrast, pool conditions are controlled, but a pool also demand a flip turn every 25 or 50 meters and swimming constantly for 72 hours in chlorinated water must impact your tongue, lips, and mouth at least comparably to salt water in the open water.
In any case, two-time Olympic swimmer (2008 and 2012) and sports psychologist Karolina Szczepaniak (33, Poland, World Aquatics bio here) swam for 72 hours straight, covering 177.865 kilometers over 7,115 lengths in the pool at the Academy of Physical Education in Warsaw, Poland, setting a new Guinness World Record on March 9th. She made the attempt in a study of the limits of human mental strength under conditions of extreme fatigue – an area that she has been studying for years.
“Physical limits are only a prelude to a real challenge,” she explained. “With such a long effort, there comes a moment when the brain starts to shut down in defense of death. Rationality then says ‘stop’, and the body sends out alarm signals. The hardest moment happened halfway through the swim. After 36 hours of swimming, I realized that I still has the same amount of time in the water remaining as I had already swum. This presented a huge mental burden.”
Szczepaniak has previously explored the outer reaches of extreme swimming. She also set a Guinness World Record for 48 hours of continuous swimming when she covered 149.025 km. She started off as a swimmer in the pool as a 200m, 400m, and 800m freestyler…and then starting to do 12-hour and 24-hour pool marathon swims…as well as a Baltic Sea attempt from Poland to Öland, Sweden that ended after 57 hours and 140 km in August 2025. It was a charity swim to raise money for prosthetics for children without arms.
Part of her training included swimming in 48 hours in a 25m pool. Her 149.02 km distance was a Guinness World Record, set in Warsaw, Poland in February 2025.
Her latest feat was also a charity swim that raised 35,000 PLN for the Open Arms Foundation where 11-month-old Amelia, who suffers from a very rare genetic disease, is treated.
For more information, visit SwimmPL.com.
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