Černé jezero (, meaning "Black Lake") in the

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

is the largest and deepest natural

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

in the

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

. This

triangular A triangle is a polygon with three corners and three sides, one of the basic shapes in geometry. The corners, also called ''vertices'', are zero-dimensional points while the sides connecting them, also called ''edges'', are one-dimensional ...

lake surrounded with

spruce A spruce is a tree of the genus ''Picea'' ( ), a genus of about 40 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ecosystem, boreal (taiga) regions of the Northern hemisphere. ''Picea'' ...

forest is located about 6 km northwest of

Železná Ruda Železná Ruda (; ) is a town in Klatovy District in the Plzeň Region of the Czech Republic. It has about 1,600 inhabitants. It is one of the important sports and tourist centres of the Bohemian Forest. Administrative division Železná Ruda con ...

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

Würm glaciation The Würm glaciation or Würm stage ( 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 glacial period in the ...

. 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 o ...

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

tributary A tributary, or an ''affluent'', is a stream or river that flows into a larger stream (''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 into which they ...

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 single ...

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 in which 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, ...

of the

Elbe The Elbe ( ; ; or ''Elv''; Upper Sorbian, Upper and , ) 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 Republic), then Ge ...

, which finds the

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

, while Čertovo jezero just 2 km away drains into the

Danube The Danube ( ; see also #Names and etymology, other names) is the List of rivers of Europe#Longest rivers, second-longest river in Europe, after the Volga in Russia. It flows through Central and Southeastern Europe, from the Black Forest sou ...

and thence the

Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea 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 bound ...

. 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, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

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

Iron Curtain The Iron Curtain was the political and physical 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. On the east side of the Iron Curtain were countries connected to the So ...

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 i ...

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 Repu ...

StB State Security (, ), 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 dealt with any activity that was considered oppositio ...

in collaboration with the

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

KGB The Committee for State Security (, ), abbreviated as KGB (, ; ) was the main security agency of the Soviet Union from 1954 to 1991. It was the direct successor of preceding Soviet secret police agencies including the Cheka, Joint State Polit ...

covertly sank cases containing old captured Nazi SS

RSHA The Reich Security Main Office ( , RSHA) was an organization under Heinrich Himmler in his dual capacity as ''Chef der Deutschen Polizei'' (Chief of German Police) and , the head of the Nazi Party's ''Schutzstaffel'' (SS). The organization's stat ...

documents in the lake and subsequently "accidentally discovered" them there. This came to light in ''The Deception Game'', published in 1972 by

Ladislav Bittmann Lawrence Martin-Bittman (14 February 1931 – 18 September 2018), formerly known as Ladislav Bittman, was an American artist, author, and retired professor of disinformation at Boston University. He was best known for his 1983 book, '' The KGB an ...

.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 Berounka basin {{Plzeň-geo-stub