The Bermuda Triangle
Turn the crank and watch the object floating in the liquid.
How does it work
Initially the object floats because its average density is less than the density of the liquid. By turning the crank, you produce air bubbles which reduce the average density of the liquid. When it becomes less dense than the object, the object sinks.
One hypothesis concerning the “Bermuda Triangle” – the area in the Atlantic Ocean near Bermuda where many ships and aircraft have mysteriously disappeared – holds that eruptions of methane from underwater deposits are responsible for the accidents. Methane escaping to the surface in the form of bubbles could cause the ships to lose buoyancy and sink.