Lake Yanisyarvi

{{short description|Lake in Republic of Karelia, Russia}}

{{expand Finnish|date=June 2023|topic=geo}}

{{expand Russian|date=February 2024|topic=geo}}

{{Infobox lake

|name=Yanisyarvi

|image =Janisjarvi crater lake 01.jpg

|caption =

|image_bathymetry =

|caption_bathymetry =

|location = Republic of Karelia

|coords = {{coord|61|58|N|30|55|E|type:waterbody_region:RU-KR_scale:500000|display=inline,title}}

|pushpin_map = Russia#Russia Karelia

|type = Impact crater lake

|inflow =

|outflow = Jänisjoki

|catchment =

|basin_countries = Russia

|length =

|width =

|area =

|depth = {{convert|11.6|m|abbr=on}}

|max-depth = {{convert|57|m|abbr=on}}

|volume =

|residence_time =

|shore =

|elevation =

|islands =

|cities =

}}

Lake Yanisyarvi ({{langx|ru|Янисъярви}}; {{langx|fi|Jänisjärvi}}) is a lake in the Republic of Karelia, Russia, located north of and draining to Lake Ladoga.

The basin of this somewhat circular lake was formed by meteorite impact 700±5 million years ago during the Cryogenian period. The crater is {{convert|14|km|mi|sp=us}} in diameter.{{cite Earth Impact DB|name=Jänisjärvi|linkname=janisjarvi|accessdate=2009-08-19}}

Prior to World War II, the lake was thought to be the second known volcanic caldera in Finland (the other was Lake Lappajärvi). Both were eventually recognized as impact craters.