Fill a cocktail shaker halfway with ice. Pour the dark rum, light rum, passion fruit juice, lime juice, orange juice, triple sec, and grenadine into the shaker. Place the lid on and shake vigorously until the drink is chilled.
2 ounces dark rum, 2 ounces light rum, 2 ounces passion fruit juice, 1 ounce fresh lime juice, 1 ounce fresh orange juice, ½ ounce triple sec, 2 teaspoons grenadine