Coconut water contains about 570 milligrams of potassium in an 8-ounce serving. A banana and a sweet potato have about the same amount; a white potato has 900 milligrams of potassium.
Unsweetened coconut water has about 50 calories per cup. Adding fruit juice adds calories.
A medium banana has about 90 calories. And a white potato that's 21/4 to 31/4 inches in diameter has about 130 calories.