Click on the image to view a QuickTime movie.

The diver consists of an irregularly shaped hollow glass test tube. An air bubble is trapped within the tube. Some latex is stretched over the top of the water-filled cylinder. When you press on the latex, the water pressure inside the cylinder is increased, the air bubble in the diver is compressed, and the resulting loss of buoyant displacement causes the diver to fall in the cylinder.

Depending on atmospheric conditions, it is possible to have the diver go to the bottom of the cylinder, and stay there. If this fortunate, rare occurrence happens, you can then show the temperature dependence of the density of water by warming the water with your hand...causing the diver to rise again.

This demo can be found in cabinet D on shelf 3 of the UCSD PUL Demo Room (WLH 2015).