If (or rather when) the polar ice caps melt, will they occupy more, the same or less volume?

Somehow all options seem possible to me. I don't assume they are just big ice cubes floating on the poles. So, if a huge mountain of submarine non-floating ice melts, wouldn't it occupy less space? But if the mountain is above the sea level, that's a new mass of water entering the sea.

Obviously, in a real case scenario other factors would be relevant too, like warmer water occupying more space than cold water. But I'm interested in this factor isolated from the rest.