The fact that you can do this is testimony to the high surface tension of water. Water is essential to all living organisms So far as we know, every living organism on the planet, from the simplest virus to the largest whale, vitally depends on water. All the plants, all the animals, all the bacteria contain water. It is the blood of life and it connects all of us in one common thread. Water then is not just a spiritual entity, but a living, breathing, and thinking being.
Ice floats because it is less dense than water.
It is an expression of the amount of molecules packed into a particular volume of space. Think about a cereal box that is packed by weight not volume. When the cereal is loaded into the box, the box is full and has a certain density, for example, one pound of cereal per box. As the box is shipped and the cereal settles, the box is no longer full. The cereal grains are packed closer to each other.