The unique property of water is that it starts freezing from the top to the bottom, while most

other substances freeze from the bottom to the top. This is the reason why the water allows the ice to float on top of the water. When the temperature starts decreasing, volume decreases, and as a result, the density of the substance increases but water shows anomalous behaviour.

Water has weird anomalous behaviour in the temperature range of . When we start cooling any liquid, as we approach its freezing point, the density of the fluid increases until it becomes a solid. But, for water, we find that the max density is at instead of (its freezing point).

Due to this when the water in a water body starts freezing, the frozen solid part floats on the liquid since it's lighter. This solid chunk of ice at acts as an insulator, keeping the water below at and preventing it from freezing. This is the reason why a lot of aquatic life in colder countries is able to survive even during winter when the atmospheric temperature goes below freezing.