How Dense Is Water?
Viscosity is not the same thing as density. Viscosity describes the degree of internal friction of a liquid. Density is a measure of the mass per volume of an object, and in terms of water, ignores hydrogen bonding. Density, however, is of vital importance to marine organisms because, living in water, they don’t require extensive supportive structures, such as the massive bones or strong trunks of land animals and plants. As most divers learn in their training, water is 800 times more dense than air, which provides quite a lot of support if you can figure out a way to live in it. This is why creatures like whales can survive, even swim gracefully at sea, yet could not survive on land because they would be crushed by their own weight. This even applies to plants. Giant kelp (Macrocystis pyrifera), for example, which can reach lengths of 200 feet/60 m, does not have, or need, the extensive root systems and sturdy wooden structure of a tree. It is supported entirely by numerous air-filled
