• Scuba divers wear BC (buoyancy compensator) equipment to adjust and control their buoyancy while underwater.
• Freedom Ship, an ocean vessel in development, will be the world's biggest ship floating on water. At one mile long and 25 stories high, engineers envision it as the first ever floating city, with 50,000 permanent residents, a hospital, parks, schools, and shopping malls. The ship will circle the world every two years in a never-ending cruise.

Here's what he realized: The water level in the bathtub rose when Archimedes climbed in, because things put into water always displace the water at least a little bit to make room. When the weight of the object is more than the water it displaces, it sinks (negative buoyancy). However, when the object is lighter than the water it displaces, it floats in the water (positive buoyancy).

Cruise ships, which are heavy, float because par ts of the boat that are underwater are hollow and contain just air. This adds to the ship's size, but not its weight. Thus, the weig ht of the water the ship displaces becomes more than the ship's weight, and as a result, the ship floats. Submarines are able to both float and sink. A submarine resting on the surface has special ballast tanks filled with air. When it wants to sink, the sub lets in seawater to fill the ballast tanks and make the sub heavier. To rise once more, compressed air is blow n into the tanks, forcing out the water and making the submarine lighter.

STAYING AFLOAT
Applying the principles of buoyancy is what keeps a huge boat above water. In the same way, drawing on tradition is what has kept the Jewish people afloat for thousands of years. According to the Talmud, a parent is obligated to teach a child cer tain things, including how to swim, “lest the child take a boat trip and it sinks and [the child] be put in danger if he or she does not know how to swim” (Rashi on Kiddushin 29a). Knowing how to swim saves us in dangerous waters. We must also learn how to stay afloat in the challenging waters of life. Torah, Jewish living, and tradition are our life preservers, providing that inner buoyancy. And the way to teach the next generation how to “swim” is by passing on the beliefs and practices of our traditions.