The investigations are based on two data sets from the Bornholm Basin and include high-resolution CTD, shear microstructure, and velocity data. A highly turbulent and strongly stratified bottom boundary layer (BBL) of a few meters thickness develops, which exhibits high mixing rates and a bulk mixing efficiency that is comparable to the interior value of 0.2. The BBL turbulence was found to be suppressed within the halocline in summer, and does therefore not contribute to cross-halocline mixing in this region.