The accumulation Komarnik Lake is located approximately 2 kilometres west of Lenart in Slovenske gorice. It was first mentioned in records in the 16th century, when the Herbersteins from Hrastovec used it to breed fish. In the 1960s it was repurposed into a flood control reservoir and reinforced with an embankment on the western side. It encompasses 25 hectares and has an average depth of 1.5 metres. To the east of the lake lies the Črni les forest, to the southeast grasslands and intensely cultivated fields. After the Pesnica river had its stream regulated and the area of the Pesnica valley was ameliorated, the lake with its immediate surroundings became the last haven and important habitat for some animal species and the sole habitat for many rare and endangered plant and animal species. Aquatic birds in particular are highly diverse, as for them the lake represents one of the most important nesting sites in Slovenia. Otters also call the area around Komarnik Lake and its surrounding streams and ponds home. A pathway with information panels surrounds the lake, along with two bird-watching posts. The lake can be accessed in two ways: either by parking at Črni les inn by the Maribor-Gornja Radgona road or by parking underneath Hrastovec castle.