Cut the rind from the whole watermelon; discard rind. Cut 13 cups of 2-inch cubes from the watermelon flesh; cut the remaining watermelon into slices and reserve for a garnish.
In a blender combine about one-third of the watermelon cubes, 1 cup of the blueberries, and 1 cup of the cold water. Cover and blend until smooth. Strain through a fine-mesh sieve into a very large pitcher or very large glass jar. Discard solids. Repeat twice.
Stir lime juice and the 2 tablespoons honey into strained fruit mixture. If desired, add additional honey to taste. Serve immediately or chill until ready to serve.
Serve over ice. Garnish with additional blueberries, the watermelon slices, and lime wedges. If desired, serve with additional honey.