Adam, the enclosed play area and the old Sports Deck was taken up by the first set of penthouse suites that were added at the end of 1972. The small pool in the photo was located in the aft, starboard corner of the enclosed play area (you can see the propeller of one of the life boats for orientation).
For reference, the area seen in the photo of the little girl in the yellow dress playing shuffle board is the forward, starboard side of the Sports Deck. The enclosed play area outside of the Children's Room is the aft end of the old Sports Deck.