//Well, if something is like I think, maybe I found a way to make a hole. It would be unsightly, but it's better than anything.
It consists of being underwater inside the ball, then we stick an arm out of the water and, while the rest of our body is underwater, we punch a hole.
Again, cracks might appear that can make the water go out and stuff, and we can't be sure we can make a hole if we aren't completely underwater... but hey, it's an idea, I think.