A rational entrainment function for a subcritical dense bottom current is outlined. As an example the formula has been used to some orders of magnitude calculations of the deep water currents from the Darss Sill to the Stolpe Channel. It is shown that the salt and oxygen supply to the deep water of the Baltic Proper during a »normal« year stems from this bottom current and its entrained water. The renewal of the deep water in the Baltic Proper can be traced in the Bornholm Basin, and hence it is strongly recommended, that continous measurements of salinity, temperature, oxygen, phosphate etc. are performed in the Bornholm Basin, especially in the highly entraining area just north of Bornholm.