If you have ever gone swimming in an ocean, or better yet, in Great Salt Lake, Utah, you may have noticed that it was easier to float in the ocean or in Great Salt Lake than in a pool or freshwater lake. Why is this? In the first part of this Activity, you will construct a hydrometer—a device that allows you to compare the densities of different liquids. In the second part of this Activity, you will use your hydrometer and an egg to monitor the effects of salt in water.