Learners use a commercially available toy to experiment with density. They fill a chamber in the toy submarine with baking powder and release it into a tank of water. The material making up the submarine is more dense than water, so it dives at first. As the water reacts with the baking powder, gas bubbles are formed and lift up the submarine. When the submarine surfaces, it tilts and the bubble of gas escapes, so the submarine dives again. The whole process repeats until all the baking powder has reacted. A real submarine operates under the same density principles. This activity is part of the Chemistry of Toys unit in OMSI's Chemistry Lab. Cost estimates are for 100 uses.