Fill a large cocktail glass with crushed ice.

Drizzle grenadine in the bottom of the glass.

Fill a cocktail shaker with ice.

Add pineapple juice, orange juice, light rum, Grand Marnier, lemon juice, and lime juice to the shaker.

Vigorously shake the mixture for 10-15 seconds.

Hold a large spoon over the grenadine in the cocktail glass, against the edge, facing down.

Slowly pour the liquids from the shaker over the back of the spoon, allowing it to settle on top of the grenadine to form a layer.

Float the dark rum on top by following the same spoon method.

Garnish with fruit, a straw, and a paper umbrella.