Staggering onto the beach, partly from exhaustion and partly from the inner-ear disorientation after being horizontal in cold water for 55 hours, Polish swimmer Bartlomiej Kubkowski had just swum 160km across the Baltic Sea between Sweden and Poland. It was the former competitive-swimmer-turned marathoner’s fifth attempt at the unique challenge.

Bartlomiej Kubkowski takes a brief break in the water. Photo: Bartlomiej Kubkowski
To complete the nonstop swim successfully, he had to walk onto the beach under his own power. He also could not touch his safety boat or sleep in the water — if that’s even possible — during that time. His support crew could pass him food and fluids on the end of a long pole during the swim, however.
Kubkowski left on Friday from the coastal Swedish town of Kaseberga and came ashore in Dziwnów, Poland, on Sunday.

Kubkowski had been trying the 100-mile crossing every summer since 2022. Each time, he drew a little closer. Last year, he came within 15km of Poland before fatigue and worsening weather forced him to stop, according to Eurosport.
The year 2025 wasn’t entirely unsuccessful, though: He did break the record for the longest distance swum in a pool over 24 hours — 103.6km.
Crossing the Baltic, however, has been his hardest project to date. No one had done it before. At the same time as Kubkowski started, however, fellow Pole and former Olympic swimmer Karolina Szczepaniak also tried, via a slightly different route. She swam for 58 hours but had to stop 40km short of the Polish coast.
According to the news site Notes From Poland, Kubkowski’s swim came close to breaking the longest-ever continuous, unassisted open-water swim — the 168.3km done by American Sarah Thomas in 2017 in Lake Champlain, between New York and Vermont.