In water unlike other substance the liquid state is denser than the solid state so an increase in pressure encourages ice to melt whereas for other substance increasing the pressure encourages the substance to stay as a solid.
The most unusual thing about the way water changes from one state to another is that its liquid state is denser than its solid state, so increased pressure actually encourages ice to melt. This is unlike most substances, in which increased pressure encourages solidification because the solid state is the most dense.
