I eat coconut chunks on a more or less daily basis. They're great for recharging the body as part of a post-workout snack, they're full of all sorts of nutrients and shit, and they just taste good. Given how often I eat them (not to mention shredding some on occasion to mix in with some cooking), it only makes sense for me to peel them from mature coconuts for myself rather than buying ready packages. The quantity from a single package is about what comes out of a typical mid-sized coconut, but the price is about 50-100% higher for the convenience, and you don't even get to drink the water.
Given how often I get asked about how to actually peel a coconut, I figured it'd make sense to do a post on it rather than needing to explain it every time.
The first step is to pick out the coconuts. I'm not 100% successful with this, but I've learned a few tricks to help with finding good ones. The biggest key is to avoid any visible discoloration (slight color gradients on the shell are fine, but any black or white areas are a major warning sign). Unfortunately, this isn't always as easy as it sounds because the coconuts around here are usually covered in plastic wrapping that makes it hard to tell what it really looks like, but I try your best. Other factors for judgment are the weight (similar to pomegranates, being heavier at the same size is a good sign) and the water content (if I can't hear any sloshing when I shake it, I assume it's no good). Lastly, if I've got access to the bare shell, it should feel and smell dry. After all of that, if I have two that seem about equally good, I go with the one that has a lighter overall color. Again, this isn't a perfect method, but it works out for me at least three quarters of the time.
Once that's all taken care of and I'm ready to go to work at home, the first step is to make a hole in it in order to drain the water. If you look at the three spots that make the "face" on the coconut, two of them will tend to have more pronounced outer ridges than the third. That third spot is the softest part of the shell. I've heard of people using a sterilized nail and a hammer to make a hole through it, but I prefer to use a corkscrew with arms/wings, like this (note: I didn't buy mine from that store and can't comment on what kind of quality to expect if you get one from there; I'm just using it for the image). A regular corkscrew can work, too, but having the removal mechanism on it makes it a lot easier.
After the shell is punctured, I pour the water through a tea strainer and into a glass. There's nothing terribly special about the strainer. You could just as well use any other clean mesh or probably even something like cheesecloth, or you can just pour it out without any straining, too. I just prefer to limit how many little pieces of shell get into the water. Regardless of which method you choose, take a taste of water. If the flavor is sweet, neutral, or a little nutty, that's typically a sign that it's a good coconut. If it's a bit salty or sour, that's not damning, but don't get your hopes up for that one. If it tastes like vinegar or spoiled milk, just throw it out.
This next part is optional (I've skipped it at times for one reason or another), but I like putting it through a thermal cycle in the oven. The shell and the flesh have different thermal expansion coefficients, plus the shell will sometimes crack on its own when it's cooling, so this extra step can help make things easier with minimal effort. There's no exact science behind how to do the thermal cycle. While I'm baking something else, I'll throw the coconuts in there in a ceramic bread pan for about 10-15 minutes and then set it aside until it's cooled back to room temperature.
IMPORTANT SAFETY NOTE: Never put a coconut in the oven (or expose it to another other significant heat source) without putting a hole in the shell first! If you do, there's a significant risk of turning it into a grenade, because the trapped water will turn into pressurized steam. Think of it as the inverse of the "never put a sealed glass container with water inside in the freezer" rule (and if you've never heard of that, well, now you have, because the fact that water expands on freezing is another way that it can cause explosions after a change of state).
In any case, when I'm ready to proceed, I grab a hollow edge cleaver (any heavy blunt object can work). Using the back edge of the cleaver, I pretty much just give the coconut a good smacking until it breaks apart. Working from existing cracks is ideal (similar to hammering a nail into soft wood, just controlling the cleaver as it falls by its own weight is usually enough to make the crack propagate), but if that's not an option, it's just a matter of pounding away until I make my own cracks. In either case, I keep hitting it until I've broken it into pieces that are no larger than roughly four inches in diameter.
On rare occasions, the shell will separate completely from the flesh on its own, and I'll be done at this point. However, in most cases, I'll need to pry at least some of the flesh off of the shell. I use a butter knife for this for two reasons. Firstly, it's just safer than using a sharp knife, since slips do happen at times and it's not worth risking a serious finger or hand injury. Secondly, butter knives tend to have a thicker blade that's free of notches or serrations, so they're less likely to bend or break when I run into a particularly stubborn piece (and I've bent/broken enough steak knives that, again, I'd rather not take the risk). There's really nothing special to this step, perhaps aside from looking over the pieces to make sure that they're white. The brown skin on the outside is safe, and there's probably going to be some brown dust from breaking apart the shell, but there shouldn't be any red/green/black/etc. spots. Sadly, you'll sometimes find one that's started to rot between the shell and the flesh, and there's nothing that can be done about that other than to cut away the bad parts.
And that's it! It might sound like a big job when it's written out like this, but it's really not so bad. Not counting the time to heat it and let it cool down, I can typically go from a plastic-wrapped coconut to a container of peeled pieces in five to ten minutes, with maybe twenty minutes as the upper limit if it's a very stubborn one.
As an extra note, once you're done, keep it in the refrigerator. The pieces can last for maybe a day if you leave them out, but take my word for it that you don't want to end up biting into a piece only to feel a slimy film on it after it's in your mouth. To the person who knows why I'm saying this: yes, I still feel bad about not having mentioned it to you upfront.
Now, if any coconut experts happen to read this post, I've got a question for you: what can I do with the leftover shell (preferably without having to grind it into tiny pieces first)?