Flathead Lake is about 370 to 371 feet deep at its deepest point , with an average depth of roughly 165 feet.

Quick Scoop

  • Maximum depth: about 370–371 feet.
  • Average depth: about 164.7–165 feet.
  • Size context: it’s one of the largest natural freshwater lakes west of the Mississippi River.

For a simple mental picture, that deepest point is roughly the height of a 35-story building below the surface.