Ever since Archimedes ran down the streets of ancient Greece shouting, “Eureka!,” scientists have understood that a submerged body displaces a volume of water equal to its own volume. Scientists also came to realize that if a body weighed less than the water it displaced, the body would float. Although this knowledge has been around for nearly 2,500 years, many students still have difficulty explaining how a vessel made of a heavier-than-water material, such as steel, remains afloat. The following tried and true activity provides students with a hands-on experience that explains the principle of buoyancy.