Deepest Lakes in Wisconsin: Top 25 Ranked by Depth (2026)
Green Lake in Green Lake County is the deepest natural inland lake in Wisconsin. Below: the 25 deepest monitored Wisconsin lakes ranked by maximum depth, with water quality grade for each.
Top 25 Deepest Lakes in Wisconsin
Ranked by maximum recorded depth (feet).
Why Wisconsin Has Deep Lakes
Wisconsin's deepest lakes cluster in two regions: the Northwoods (Vilas, Oneida, and Forest Counties) where Wisconsin glaciation left deep kettle lakes, and a few large kettle lakes in the eastern part of the state — most famously Green Lake.
Depth allows thermal stratification in summer, which preserves cold, oxygen-rich bottom water — the habitat trout and lake whitefish need. Most Wisconsin lakes deeper than 60 feet support coldwater species.