To get the ball rink, you have to beat the game. After you beat the game, you will appear in a strange place in a ball mode and will show credits. If you somehow quit that place, don't worry. It's in bikini bottom by Sandy's house.
If you have enough golden spatulas than go to
where it shows a crossing sign that will not let
you get in. It will open and you have to fight
Sandy. Beat her and you will get prizes. One
of them is Bubble Bowl.