What is that on Deck 10?

[Lumiere999]

As we are getting closer to cruise time, I am trying to familiarize myself with the ship. I cannot for the life of me figure out what is that on the deck 10 layout. It is in back of the aft elevator lobby, a round circle with what looks like a pool slide. It is not labeled so I am just curious as to what it is.

 

[tstobb]

It's the smokestack and the slide into the Mickey Pool.