Molten rock - lava - flows out of a crack in the Earth's crust at Iceland. Iceland is an island in the Atlantic ocean. No volcano has been formed at the crack. The lava just flows out. The crack is very deep - 20 000 meter, we are told, and cannot be plugged. If you ask the Iceland experts how the lava is heated up down below Iceland, they haven't a clue. They suggest that the complete Earth below the crust is hot, liquid lava. The Earth is 99.9 % liquid lava below a thin crust we are walking on.
I agree 100% . A flat Earth cannot float on hot, molten lava.