Lay your watermelon on a clean, flat surface.
Slice in half.
Slice your half in half. Your watermelon should now be chopped in four quarters.
Slice in one inch sections vertically (from top to rind.)
This part is where it might get a little tricky. You are going to slice horizontally (across), but position your knife at an angle parallel to the other side of the watermelon.
Keep going across in one inch sections.
Rotate your watermelon slice and do the same thing to the other side.
Once you do this, the watermelon will be cut in neat, tidy squares.
Flip over your watermelon and the cubes will just fall out! Use your knife to slice around the edge of the rind to cut out any pieces that remain. Serve and enjoy!