 It's totally legal. They can hold between 7 and 34 ounces of coconut water inside if you want the real thing and not something with a label on it. Wow. TSA does. It's amazing what they allow and don't allow. That's why I can't wait until I'm sitting on a plane and the guy next to me pulls out his coconut and whatever tool he needs. I am now nine days away from a Cleveland trip with coconuts, man.