How fast ice melts depends on the temperature it is exposed to and what substance it is in. Ice melts at different speeds depending on if it is in air or water.
Ice generally melts quicker when it is in water, assuming they are at the same temperature. This is because water molecules are more dense; this means that more water comes into contact with the surface of the ice. Secondly, water has a higher capacity for heat. However, if the air is moving quickly across the surface of ice, then the molecules have more chances to interact with the surface and may be able to melt the ice quicker.