Step 1

Combine watermelon, mint leaves and lime juice in a cocktail shaker and muddle until leaves are broken up slightly and watermelon is crushed.

Step 2

Fill shaker with ice, add the simple syrup and rum.

Step 3

Shake until ice cold.

Step 4

Fill glasses half full with ice; pour contents of shaker (do not strain) including ice into glasses.

Step 5

Top with chilled club soda and gently stir.

Step 6

Garnish with watermelon and mint.