A lake to the northeast of Battle Ground, Washington, and a state park of the same name. Battle Ground Lake, much like Mount Tabor in Portland, is a caldera of an ancient volcano, although unlike Mount Tabor, it has filled in with water. Although not very wide across, the lake is very deep. (When I was a child, I was told it went down "forever", but that was probably an exagerration.)
Battle Ground Lake's latest claim to fame has been that it was responsible for the largest case ever of water born E Coli in United States history.