Add 2 cups of crushed or cubed ice to your blender or food processor. The ice should be cold and ready to blend into a smooth, slushy consistency. If using cubed ice, pulse it a few times first to break it into smaller pieces for easier blending.
Pour 1 cup of blue raspberry syrup over the ice. If using unsweetened Kool-Aid, mix the powder with a small amount of water first to create a concentrated syrup. The blue color should be vibrant and evenly distributed across the ice.
Add 0.5 cup of coconut syrup or cream of coconut to the blender. This ingredient creates the signature tropical flavor and creamy texture that makes Sonic's Ocean Water Slush so distinctive. The coconut will add richness and balance the tartness of the blue raspberry.
Pour in 0.75 cup of cold water or lemon-lime soda, depending on your preferred consistency. If you want a thicker, more frozen slush, use less liquid; for a thinner, more drinkable consistency, add more. The soda will add extra sweetness and carbonation if desired.
Blend on high speed for 30-45 seconds until the mixture reaches a smooth, slushy consistency with no large ice chunks remaining. You should hear the blender working steadily, and the mixture should look uniform in color with a thick, frozen texture. Stop and stir if needed to ensure even blending.
Pour the blended slush into a tall glass, filling it about three-quarters full. The mixture should be thick enough to hold its shape but still pourable. The color should be a beautiful bright blue with hints of the coconut cream swirled throughout.
Top with a splash of additional lemon-lime soda if desired for extra fizz and sweetness, mimicking the Sonic version. This step is optional but adds authenticity to the copycat recipe. Stir gently to combine the soda with the slush.
Insert a wide straw or spoon into the slush and serve immediately while it's still frozen and cold. The drink should be consumed right away for the best texture and flavor. If it begins to melt, simply re-blend or add more ice as needed.
