The "underwater volcano" is a common science project meant for children and those new to physics. It is designed to demonstrate how the relative temperature of water creates currents in the ocean.Continue Reading
Hot water is less dense than colder water and tends to rise to the top. Eventually, convection causes the temperatures of these mixed water types to stabilize. The experiment demonstrates how water that is at different temperatures can move at different speeds by using hot and cold water mixed together in a jar.
Food coloring or dye is used to differentiate the hot water from the cold water. A larger jar or bottle (such as a standard 2 liter soda bottle with the top cut off) is used to hold the cold water, and the hot water is contained in a smaller glass bottle that has a lid with some small perforations (like a salt shaker). The hot water jar is lowered into the bottle of cold water by using a piece of string or yarn. Once inside, the hot water should erupt to the top of the cold water, just as a volcano erupts. In time, the temperature evens out and the water becomes a uniform color.Learn more about Volcanoes