What are Floating Continents ?

The solid continental plates of Earth's crust float on the endless seas of molten mantle rock beneath them.
Archimedes' principle explain why. Archimedes' principle says that the buoyancy force acting on an object is equal to the weight of the fluid that object displaces.
So how pieces of Earth's crust ride in the dense fluid-like material of the mantle depends on both their volume and density. Continental crust, of lower-density rock than seabed rock, floats higher.
At the same time, large and heavy features of Earth's crust—Greenland, for example, covered with an enormous volume of ice—may push deeper like the submerged portion of an iceberg.
They may not project very high above the mantle, but they do float.