Jiri Polansky Wins IISA Polish Championships - Silesia Winter Swimming 1K Courtesy of International Ice Swimming Association, Katowice, lake Szlomiok (Dolina Trzech Stawów), Poland. The IISA Polish Championships - Silesia Winter Swimming 2020 event was held at Katowice in Lake Szlomiok (Dolina Trzech Stawów), Poland where the water temperature was