Černé jezero (german: Schwarzer See, meaning "Black Lake") in the

Bohemian Forest The Bohemian Forest, known in Czech as Šumava () and in German as Böhmerwald, is a low mountain range in Central Europe. Geographically, the mountains extend from Plzeň Region and South Bohemia in the Czech Republic to Austria and Bavaria in ...

is the largest and deepest natural

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

in the

Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...

. This

triangular A triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry. A triangle with vertices ''A'', ''B'', and ''C'' is denoted \triangle ABC. In Euclidean geometry, any three points, when non- collinea ...

lake surrounded with

spruce A spruce is a tree of the genus ''Picea'' (), a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal (taiga) regions of the Earth. ''Picea'' is the sole genus in the subfami ...

forest is located about 6 km northwest of

Železná Ruda Železná Ruda (, german: Markt Eisenstein) is a town in Klatovy District in the Plzeň Region of the Czech Republic. It has about 1,600 inhabitants. It is located in the Bohemian Forest, close to the border with Bavaria and the German town Bayeris ...

under a 300-metre-high cliff on Jezerní hora (1,343 m). It is of

glacial origin A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betwe ...

, a product of the

Würm glaciation The Würm glaciation or Würm stage (german: Würm-Kaltzeit or ''Würm-Glazial'', colloquially often also ''Würmeiszeit'' or ''Würmzeit''; cf. ice age), usually referred to in the literature as the Würm (often spelled "Wurm"), was the last g ...

. The water in the lake is

oligotroph An oligotroph is an organism that can live in an environment that offers very low levels of nutrients. They may be contrasted with copiotrophs, which prefer nutritionally rich environments. Oligotrophs are characterized by slow growth, low rates of ...

ic. There is a natural outflow through ''Černý potok'', a short stream which is a

tributary A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainage ...

of the Úhlava River. The main European

water divide A drainage divide, water divide, ridgeline, watershed, water parting or height of land is elevated terrain that separates neighboring drainage basins. On rugged land, the divide lies along topographical ridges, and may be in the form of a singl ...

runs across the mountain just above the lake. As a consequence, Černé jezero belongs to the

water basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, the ...

of the

Elbe The Elbe (; cs, Labe ; nds, Ilv or ''Elv''; Upper and dsb, Łobjo) is one of the major rivers of Central Europe. It rises in the Giant Mountains of the northern Czech Republic before traversing much of Bohemia (western half of the Czech Repu ...

, which finds the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...

, while Čertovo jezero just 2 km away drains into the

Danube The Danube ( ; ) is a river that was once a long-standing frontier of the Roman Empire and today connects 10 European countries, running through their territories or being a border. Originating in Germany, the Danube flows southeast for , pa ...

and thence the

Black Sea The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Roma ...

. The oldest pumped-storage hydroelectric plant in the Czech Republic (built 1929-1930) is located here; the lake serves as its upper reservoir.

Role in Cold War Czech disinformation campaign

Due to proximity of the

German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ger ...

border (about 1 km), access to the lake was very limited during the

Iron Curtain The Iron Curtain was the political boundary dividing Europe into two separate areas from the end of World War II in 1945 until the end of the Cold War in 1991. The term symbolizes the efforts by the Soviet Union (USSR) to block itself and its s ...

era. This was exploited by communist

secret service A secret service is a government agency, intelligence agency, or the activities of a government agency, concerned with the gathering of intelligence data. The tasks and powers of a secret service can vary greatly from one country to another. For ...

s in

Operation Neptune Operation or Operations may refer to: Arts, entertainment and media * ''Operation'' (game), a battery-operated board game that challenges dexterity * Operation (music), a term used in musical set theory * ''Operations'' (magazine), Multi-Man ...

(1964) when the

Czechoslovak Czechoslovak may refer to: *A demonym or adjective pertaining to Czechoslovakia (1918–93) **First Czechoslovak Republic (1918–38) **Second Czechoslovak Republic (1938–39) **Third Czechoslovak Republic (1948–60) **Fourth Czechoslovak Repub ...

StB State Security ( cs, Státní bezpečnost, sk, Štátna bezpečnosť) or StB / ŠtB, was the secret police force in communist Czechoslovakia from 1945 to its dissolution in 1990. Serving as an intelligence and counter-intelligence agency, it de ...

in collaboration with the

Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...

KGB The KGB (russian: links=no, lit=Committee for State Security, Комитет государственной безопасности (КГБ), a=ru-KGB.ogg, p=kəmʲɪˈtʲet ɡəsʊˈdarstvʲɪn(ː)əj bʲɪzɐˈpasnəsʲtʲɪ, Komitet gosud ...

covertly sank cases containing old captured Nazi SS

RSHA The Reich Security Main Office (german: Reichssicherheitshauptamt or RSHA) was an organization under Heinrich Himmler in his dual capacity as ''Chef der Deutschen Polizei'' (Chief of German Police) and ''Reichsführer-SS'', the head of the Nazi ...

documents in the lake and subsequently "accidentally discovered" them there. This came to light in ''The Deception Game'', published in 1972 by Ladislav Bittmann.Prague Radio
"Details of Czechoslovakia's biggest disinformation operation published on web"
2007

References

Lakes of the Czech Republic Mountain lakes Klatovy District Glacial lakes Bohemian Forest {{Plzeň-geo-stub