1. Cut watermelon in half. Scoop out watermelon pulp; reserve for another use. Carefully remove outer green layer from watermelon rind using a vegetable peeler. Cut peeled rind into 1 1/2-inch cubes to measure about 4 cups.
2. Combine rind and salt in a large zip-top plastic bag. Seal and refrigerate 24 hours, turning bag occasionally.
3. Remove rind from bag; drain. Rinse rind thoroughly under cold water; drain. Place rind in a large saucepan. Cover with water to 2 inches above rind; bring to a boil. Cover, reduce heat, and simmer 15 minutes or until crisp-tender. Drain and rinse under cold water; drain well. Place rind in a large bowl.
4. Combine sugar and remaining ingredients in a large saucepan; bring to a boil, stirring until sugar dissolves. Pour hot sugar mixture over rind; let stand at room temperature 2 hours. Cover and refrigerate 5 days. Store in an airtight container in refrigerator up to 3 weeks.