While you can in fact freeze watermelon, it is important to do so correctly so you can keep it fresh for as long as you need to. You will want to first cut up your watermelon into chunks (one inch or so each) and place them on a cookie sheet which is lined with wax paper or preferably Saran Wrap.

You will also want to take the time to spray down the chucks of watermelon which you have cut up with water before you put them back into the freezer. After you have completed these steps, you will want to put them in a vacuum sealed bag and remember to only partially thaw them out before you eat them.