Since the inside of a floating structure is divided into huge number of watertight compartments in comparison with ordinary ships, for example, a floating airport of 500ha is provided with more than 10,000 compartments vs 20 to 30 in case of 300 thousands tons very large tankers, even in case of the several compartments are flooded simultaneously by an accident, the floating structure still has enough buoyancy with the remaining compartments without damage, then the floating structure could not be recognized to sink unless it would be intentionally sunk.