Abstract
Due to its inaccessibility (in winter), Lake Czarny Staw pod Rysami (Black Lake below Mount Rysy) has no series of continuous observations concerning ice phenomena. For the purpose of supplementing knowledge in this scope, ice corings were performed in the years 2010–2015. They permitted the determination of the variability of ice cover thickness on the lake’s surface. A high degree of similarity was determined in the distribution of ice cover thickness in the analysed winters (in contrast to the nearby Lake Morskie Oko). Moreover, a correlation was determined according to which the thicker the snow cover overlying the ice, the thinner the ice cover. It was determined that the mean thickness of the ice cover of Lake Czarny Staw pod Rysami is higher by approximately a dozen cm than that on Lake Morskie Oko located around 200 m lower.