You only use the white part of the watermelon rind.
The rind is hard and has to be pre-cooked in boiling water for a long time
(you would think that watermelon rind would be soft!)
Be sure too cook the rind long enough to soften it in the boiling water.
Do not cook the rind too long in the syrup, or it will get tough and leathery, instead of more tender.
Your finished product will be an old fashioned delight!