Begin by selecting a ripe watermelon; cut off the rind and chop it into cubes.

Take a Ninja Creami pint container and fill it with the watermelon cubes up to the max fill line. Mash the watermelon cubes.

Pour coconut water into the same pint container until it reaches the max fill line.

Secure the lid tightly on the pint container and place it in the freezer for 12 to 24 hours.

Once frozen, carefully remove the pint container from the freezer. Spin it using the Ninja Creami.

Check the texture; add a splash of coconut water and re-spin if too chunky.