It is a textbook knowledge that
in order to dissolve rock salt in liquid water at ambient conditions
at least nine water molecules per salt molecule
are needed. An obvious but until now 
unsolved question arrises: How many
water molecules are necessary to solvate a 
single sodium chloride molecule? In other words,
what is the smallest water cluster, in which a solvent separated
Na$^+$/Cl$^-$ ion pair becomes stabilized?
The answer based on accurate quantum chemical calculations 
is that simple extrapolation from 
the liquid is quantitatively wrong and that
the {\it hexamer} represents the smallest water species that
dissolves the NaCl molecule.