Step 1

Cut enough watermelon into 1-inch cubes until you have 8 cups. Transfer half to a blender and blend until smooth.

Step 2

Fit a fine-mesh strainer over a large bowl. Pour the blended watermelon through the strainer and press on the watermelon solids with a ladle to force more juice through. Discard the contents of the strainer. Repeat blending and straining the remaining watermelon. Rinse the blender out, then pour the strained juice back into the blender.

Step 3

Juice 6 to 9 limes until you have 3/4 cup juice. Add the juice and 3/4 cup simple syrup to the blender and blend on low speed until combined. Skim any foam off the top.

Step 4

Pour into a pitcher and refrigerate until chilled, or serve over ice. Garnish with watermelon slices, lime slices, or fresh mint.