WHY is it easier to swim in salt water than in fresh one?

 Salt plays a crucial role in making water heavier, which in turn affects its buoyancy. The greater the density or weight of water, the easier it is for objects to float in it. When an object is placed in a liquid, it floats if its weight is equal to the weight of the water it pushes out of the way. This is because the water is displaced to make room for the object. Another way to think about it is to consider the scenario of sitting in a tub of water. As you get into the tub, the water level rises, which is due to the displacement of water by your body. If you drain the water that your body has displaced, the weight of the water will be equal to the weight of your body. Hence, the concept of buoyancy is closely tied to the weight of the water and the object being placed in it.