I use coconuts a lot in my diet. Coconut meat, coconut water, coconut milk, shredded coconut, coconut flour....I think you get the idea. In Costa Rica, the ticos and ticas (natives) call the young coconuts "pipa". A young coconut has "water" inside. A mature coconut has "milk" inside. Water is mainly used to drink. There is a little bit of meat, but it is kind of slimy to just eat plain. I sometimes scrape it out and freeze it to add to smoothies along with the coconut water. If I'm not feeling that ambitious, I just give it to the dog and chickens. Milk and meat from mature coconuts is used for a wide variety of things: coconut cream, shredded coconut, coconut milk, coconut oil, coconut flour, etc.
I wanted to share what I do with the coconut water from young Thai coconuts. I freeze the water in ice cube trays to use in smoothies instead of actual ice cubes. I like to buy a box of 9 coconuts from a local Asian market (way less expensive than the health food stores). If you do this, please remember they have to be kept refrigerated until you use them. This is what you will need to start.
Next is to break open the coconuts and get the meat out.
So, take your hammer and bang away. Hit it next to the hole. It is weakest at this point. Then hit it next to that hole you just made. This should break it open pretty good. Just give it a few hard whacks slamming it down against the ground until it breaks through. Oh yeah, doing this on concrete works best.
Use a spoon to scoop out the meat; it's quite tender and easy to do, unlike the mature coconuts. That meat is really thick!
From here you can put it in a smoothie, or freeze for later use.