why do things float in salt water?

When you add salt to water, it makes it 'heavier' than regular water. This means that the water can hold up, or float, things that couldn't float in regular water. The salt makes the water dense, which means the water can hold more weight than regular water because the molecules that make up the water are closer together. When an object is denser than the water, it will sink, but if it is less dense than the water, it will float!