Lake Vištytis

Infobox_lake
lake_name = Lake Vištytis
image_lake = Lake Vistytis (Vist1).jpg
caption_lake =
image_bathymetry =
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location =
coords = coord|54|26|N|22|44|E|type:waterbody_region:LT|display=inline,title
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inflow =
outflow = Pissa
catchment =
basin_countries = Lithuania, Russia
length =
width =
area = 17.87 km²
depth =
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cities = Vištytis

Lake Vištytis ( _lt. Viśtyčio ežeras; _de. Wystiter See; _ru. Виштынецкое озеро; informally sometimes called the "European Baikal"), is a lake on the border between Lithuania (Marijampolė district) and Russia (Kaliningrad oblast). Prior to World War II it marked part of the border between Germany and Lithuania. The small Lithuanian town of Vištytis on the northern shore was named after it.

Lake Vištytis covers an area of 17.87 km² most of which is in Russia. The frontier follows the waterline along the Lithuanian shore, so bathers on Lithuanian beaches actually enter Russian territorial waters. It is situated within a picturesque landscape of forests and hills. The lake is a protected nature reserve and earns its "European Baikal" reputation because of the diversity of its unique flora and fauna.