You don't need the water, I needed to add it to post this technique. You will need:1 butcher knife, 1 large cutting surface, 1 very large bowl.
Lay the watermelon onto the cutting board on it's side and cut off one end just to expose the pink flesh.
Turn the watermelon around and cut the other side. Stand the melon up on one end so it is sitting flat.
Using your butcher knife, begin from the top and cut a section of green, curving around the midsection and down to the bottom. Try to cut where you expose the meat but not cut too far into it. Don't worry if you miss some of the rind. Place the cut-off rind into the large bowl.
Continue cutting the melon starting at the top and cutting down to remove the rind, turning the cutting board (or melon) as you go. You may miss some rind on the bottom, but no worries.
Cut the watermelon in half longways from top to bottom. (careful as this can be slippery), Turn the halves face down so that the center of the melon is now on the cutting board and it is laying flat. Now you can easily trim any remaining rind off. Now your bowl if full of rind, simply discard it and use bowl for the melon.
Begin with one half of the melon and place one hand on top with fingers and thumb spread up and out so you don't cut yourself. Slice the watermelon horizontally in half. then cut strips, turn cutting board and cut strips in the other direction to make cubes and place into the bowl. Do the same for the other half of the melon. Serve with forks and enjoy.