I just came back from Whole Foods (Sanfair) and they had pre cut young coconuts! The best coconut water to get is from young coconuts. I used to drink these all the time, but Justin was worried for the safety of my fingers (to open them you pretty much have to chop them machete style) and banned me from getting them. So I tried every brand of coconut water they sell at whole foods and found that Taste Nirvana no pulp is the best (comes in green glass bottles).
Coconut water is so good for you. It is rich in electrolytes, potassium, iron, and no added sugar. Best served cold.