Charleston Gray is a very old variety of watermelon that dates back to 1954.  It was developed by Charles Frederic Andrus, a scientist from Charleston, to be disease-resistant and wilt-resistant.  This classic variety is very sweet and has a fiberless flesh.  The rind is greenish-gray, thick and tough, and can be used for making watermelon pickles.  The fruit can range from 25-35lbs.