Hold the coconut in the palm of your hand over a sink or large bowl. The bowl will catch the coconut juice when the coconut splits open. Note the seam that runs between the "eyes." Follow the seam to the equator of the coconut. Using the blunt edge (not the blade) of a heavy knife (for example, a chef's knife, meat cleaver, machete) tap firmly around its equator as you rotate the coconut in the palm of your hand. Continue to tap and rotate until the coconut splits completely open. If it's done right, after just a few turns, the coconut will break open into two equal halves.