Underwater Volcano

    April, 2016:  

    Kids, this is a demonstration of what occurs in the ocean and what would have occurred in the formation of some islands like Hawaii. This was inspired by the “3 Scientists Walk into a Bar” Facebook page:

    Please note:  All chemicals and experiments involve an element of risk, and no experiments should be performed without proper adult supervision.


    • colored wax pieces
    • water
    • sand
    • a hot plate, fifth burner, or stove-top
    • a colorless glass vessel that can be heated (Pyrex beaker?)

    You will certainly want the help of an adult on this.

    Try this:

    • Add several chunks of the wax, the total amount equivalent to a C battery, to the glass vessel.
    • Cover the wax completely with sand and add about an inch of sand above that.
    • Add water so that you have an inch of water above the sand.
    • Add heat. As heat is added, watch closely for the wax to escape through the surface of the sand.

    The sand represents the Earth’s crust and the water symbolizes the ocean, while the wax is like the molten magma (or lava once it escapes the Earth’s crust). Magma is a liquid because it resides below the Earth’s crust in the mantle of the Earth where the temperatures can be on the order of 700ºC to 1300ºC.

    As the wax melts it pushes up against the Earth’s crust and eventually creates a fissure or crack in the crust through which it can rise. The water (once it cools) will allow the liquid “lava” to cool and solidify. The “island” that you created is probably floating on the water. This would not be the case in the middle of the Pacific Ocean. As soon as the lava hit the cold ocean water it would cool and solidify and the island would be built up from the fissure all the way to the ocean’s surface.

    To view all past “ChemShorts for Kids”, go to: