Lake Tazawa

Infobox lake
lake_name = Lake Tazawa
田沢湖
image_lake = Tazawako.jpg
caption_lake =
image_bathymetry =
caption_bathymetry =
location = Akita Prefecture
coords = coord|39|43|30|N|140|39|41|E|region:JP_type:waterbody|display=inline,title
type = crater lake
inflow =
outflow =
catchment =
basin_countries = Japan
length =
width =
area =
depth =
max-depth = 423.0 m
volume =
residence_time =
shore =
elevation =
islands =
cities =

Nihongo|Lake Tazawa|田沢湖|Tazawa-ko is a caldera lake in Akita Prefecture, northern Japan. It is the deepest lake in Japan (the maximum depth is 423.0 m). Because of its depth, it never freezes.

Formerly the lake was noted for having very clear water which could be compared to Lake Mashu in Hokkaidō. It was polluted due to the construction of a hydroelectric dam in 1940 and acid drainage from a hot spring (onsen). As a result, the indigenous fish kunimasu ("Oncorhynchus nerka kawamurae") became extinct.

The town of Tazawako is named after the lake. JR East maintains the Tazawako Line. While once the limited express "Tazawa" ran from Morioka to Akita, it was replaced by the Akita Shinkansen "Komachi" in 1997.

Several hot springs resorts can be found in the hills above the lake. Akita Prefecture's largest ski area, Tazawa Ski Area, overlooks the lake.