Algodoo

A Cartesian diver is a small device that utilizes fluid buoyancy and pressure changes to achieve sinking and floating. It typically consists of an inverted small container (often made from a straw and a pen cap) containing air and a large bottle filled with water. When the bottle is squeezed, the air above the water surface inside the bottle is compressed, forcing more water into the diver, which increases its overall weight and causes it to sink. When released, the internal air expands, expelling the water, making the diver lighter and causing it to float. This process visually demonstrates the balance between buoyancy and pressure.
This scenario is a simple reproduction of the Cartesian diver. Its imperfection lies in the fact that I did not precisely calculate the pressure inside the bottle but instead expressed the buoyancy of the diver as a single-variable function of the bottle's volume.
Nevertheless, the process of sinking and floating has been successfully demonstrated.