Most people who suffer from this misconception rely on the “melting ice in a glass” experiment. This experiment does not apply to ice caps as not all the ice is “floating” in the oceans.
Actually, the vast majority of the of the ice within the ice shelves are already below sea level. As we should know by now, this being the Flat Earth Society, the Ice Shelves rises only about 150 feet above sea level, terminating as a vertical front of ice at the coast. It's the Ice Wall described in the FAQ. Consult the expeditions of Sir James Clark Ross for a reference.
From
http://www.asoc.org/general/iceshelve.htm"The weight of Antarctica's ice is so enormous that it has literally pressed the continent two thirds of a mile (one kilometer) into the earth. Under the massive forces of their own weight, the ice sheets deform and drag themselves outward. Very large glaciers called ice streams flow through them continually, transporting ice from the center of the continent to the sea."
There we can see that the Ice Shelves extend one kilometer beneath sea level. Therefore, most of the Ice Shelves are already below sea level, less dense than the water which surrounds it.