In a cocktail shaker with ice, add Malibu coconut rum, pineapple juice, and orange juice; shake until well-chilled.
Strain into the prepared glass over fresh ice.
Slowly pour grenadine down a bar spoon so it settles at the bottom and creates a layered sunset effect.
Garnish with a maraschino cherry, pineapple wedge, and orange slice. Serve without stirring.
Notes
For sharper layers, use clear ice and keep ingredients well-chilled. Adjust sweetness by reducing grenadine or adding a splash more citrus. A highball glass works too, but the hurricane glass shows off the colors best.