Underwater Volcano 🌋 ages 3-8 🌋 All you need for this experiment are two glass containers, a rock or small object to weigh down small container, water and food coloring. Fill the large container with cold water and the small container with hot water. Place the rock in the bottom of the small container. Add food coloring to the small container. Gently place the small container in the large container and watch the eruption happen! Hot water rises to the top because the molecules in it move faste