Boats and waves between two liquids


It is a box with transparent walls, which contains two different colored liquids, that are not mixable and have very different densities. The colored liquid is denser than the transparent one. The two boat-shaped objects are composed of a material whose density is in the middle of the ones of the liquids, therefore they float on the separator surface.
Using his fantasy one can make a lot of devices working in accordance with the same principle, as shown in the clip, and we can observe waves produced by a simple mechanism operated by battery.