The lake was formed during the Würm glaciation period approximately 10,000 to 15,000 years ago.
In 1964, the lake became the site of a notorious Cold War disinformation operation known as 'Operation Neptune', where fake documents were planted to frame Western politicians.
The name 'Black Lake' refers to the dark color of the water caused by deep peat deposits and the reflection of the dense forest canopy.
It is the only lake in the Czech Republic that belongs to the Black Sea drainage basin, unlike most others which flow toward the North Sea.
The lake has been a strictly protected nature reserve since 1911.
The Jezerní hora (Lake Mountain) towering above the lake reaches an altitude of 1,343 meters.
Swimming and any water-based activities are strictly prohibited to preserve the lake's delicate ecosystem.
Černé jezero, or the Black Lake, is the largest natural glacial lake in the Bohemian Forest, situated at an elevation of 1,008 meters. The lake covers 18.47 hectares and reaches a maximum depth of 39.8 meters. Its dark appearance results from the reflection of the surrounding dense spruce forest and its high content of peat-derived organic matter. The lake is located directly below the 300-meter-high Jezerní hora rock wall. It serves as an important site for ecological study due to its distinct stratification and rare plant species. The water drains via the Černý potok into the Úhlava river, eventually feeding into the Black Sea catchment area. It is protected as part of the Šumava National Park and is located near the historical border of the former Iron Curtain.
The wooden viewing platform located on the eastern shore provides the best panoramic view of the lake against the mountain wall.
Wear sturdy, waterproof hiking boots as the trails can be muddy and rocky.
Carry plenty of water and snacks, as there are no food services available directly at the lakeshore.
Prepare for rapid weather changes; even on sunny days, the temperature can drop significantly near the water.
Attempting to swim or enter the water, as it is a protected nature reserve. Relying on digital maps without offline backups, as cell service is inconsistent in the deep valley.
Stay on marked trails at all times. Swimming, camping, and fires are prohibited. Keep noise levels low to respect the wildlife habitat.
