On the basis of the analysis of the stability of an interacting system of straight edge cracks it is shown that when the fracture strength of the ice is taken to be nonzero, there exists a minimum spacing for water-free crevasses (about 6--8 m). This spacing is, in general, much larger than the minimum crack spacing (about 1/3 m) needed in order to be able to attain the critical value of the stress intensity factor; and therefore, in general, the minimum spacing of the water-free crevasses is dictated by the stability consideration, rather than by the consideration of the stresses alone. In terms of dimensionless parameters a master chart is developed which separates stable and unstable states. It is shown that the minimum spacing decreases with decreasing fracture strength of the ice, and when the fracture strength of the ice is taken to be zero, the spacing can be very small. At this limit the penetration depth is approximately given by the value found by Nye, which is then independent of the corresponding spacing.