Coconut water is living water. Mineralized water from deep within the earth is sucked up by the roots of the palm tree, filtered up its trunk, and perfectly sealed inside a coconut. It takes the palm tree nine months to filter one liter of water up its trunk.
Coconuts are a great source of electrolytes. (...) The Food and Agricultural Organization of the United Nations' Chief of Agricultural Industries and Post Harvest Management Service says, "coconut water is a natural isotonic beverage with the same lever of electrolytic balance as we have in our blood. It's the fluid of life, so to speak."
During WWII, doctors discovered the water in young coconuts could be used as a substitute for blood plasma, because it's sterile, cool, easily absorbed by the body, and doesn't destroy red blood cells.