Difficulty: Medium

You have a rubber balloon with a string attached to it. A weight is attached to the other end of the string. You fill the balloon with enough air so that if you submerge it and the weight in water to a depth of 30 feet, the balloon will neither rise nor sink — with its buoyancy exactly balanced by gravity. You then pull the balloon and weight down another 30 feet. If you let the balloon go at this depth, will it rise or sink? (Assume that the water temperature is the same at both depths.)