Also known as Lake Kałek, it is one of the most pristine (class I and II water quality) and most beautiful lakes in the Lubusz region. The tunnel-valley lake is about 780 m long and about 410 m wide, with the maximum depth of 23.8 m. Interestingly, it is not fed by any surface tributary, but mostly by groundwaters, which is very rare for Polish lakes and also makes it exceptionally clean. With its rich fish population, the lake is a great destination for anglers and is known for its giant breams (the largest one caught here weighed well over 5 kg). Other fish species include tenches, eels, pikes, roaches, rudds, perches and carps. The local flora is dominated by deciduous trees, such as black alder, aspen poplar, silver birch or white willow. The lake was formed during the Pleistocene glaciation (commonly known as the Ice Age). The glacier eventually receded from the territory of contemporary Poland around 13 thousand years ago.