Add the frozen raspberries to the blender, ensuring they are evenly distributed.
Pour in the splash of lemon juice over the raspberries. This brightens the tartness and enhances the flavor.
Pour the coconut water into the blender, starting with half a cup for a smooth blend.
Secure the lid on the blender and pulse a few times to start breaking down the berries and liquid.
Blend on high for about 20-30 seconds until the mixture becomes icy and slushy, with a vibrant purple-red hue.
Check the texture; if it's too thick or icy, add a splash more coconut water and blend briefly again.
Once smooth and slushy, pour the blue raspberry mixture into glasses.
Serve immediately with a straw and enjoy the refreshing, icy burst of flavor.