There are many differences between freshwater and saltwater. The most obvious difference is that saltwater contains salt, or sodium chloride. Freshwater does contain a small amount of salt as well, but not enough to be considered saltwater. To be considered freshwater, the body of water must contain less than 1% salt. The salt lends itself to other differences between freshwater and saltwater. For example, because of the salt dissolved in saltwater, saltwater is also more dense than freshwater. This means the volume of the water is heavier than that of freshwater. What is interesting about this difference is that it means saltwater is also more buoyant than freshwater. This means in bodies of water with a high concentration of salt, you can nearly float! The salt in saltwater also alters the freezing point. Saltwater has a lower freezing point than freshwater because of the salt in it. Another difference concerns the animals that can survive in each body of water. Typically, most animals can only live in one or the other environment, not both.