Tracers released into the pelagic, stratified center of lakes, show that interior mixing - €”based on both mode-related internal shear and higherfrequency internal waves – is extremely weak. After horizontal spreading, the tracers "feel" the local bottom boundaries (BBL) and the basin-scale diapycnal (vertical) mixing increases by more than one order of magnitude. Balancing kinetic energy and dissipation reveals that the observed internal energetics and mixing can be explained by classical bottom friction of the basin-scale (seiches)