I have an offer in for a house with a large pool (800 SF) that I really don't want, but otherwise I like the house.  I am also hoping to be able to add on if/when our offer is accepted. 

Our initial thought had been to fill-in the pool, then build atop it.  But then we were warned that you have to effectively build a new foundation equal to the original pool, i.e., at great expense and waste of money.

Then we thought it would be simpler to convert the pool into a basement; it has a diving board and is already 8-10 feet deep.  But then we were told that it costs ~ $325/SF to build a basement because of the need to waterproof and create drainage etc.  Not sure if that quote included the cost of the above-ground structure (I hope?!).

Any comments or suggestions?
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Worst case, I think, is we would just fill-in the pool as cheaply as possible, then figure-out our options for building UP on the existing single-story house.

I seriously doubt there is any money to be saved, and all kinds of mistakes to make, in converting a pool to a basement.

Fill it in, if you must, and add on to the house.

Before you fill it in it might be woth it to dig out the walls and bring it to scrap or build a shed or something. Been there done that.

Ps: All heavy gauge galvanize.

Covered, it might make a good safe room/tornado shelter. But cheap and simple would be to fill it.

Covered as a tornado shelter? I think in that case it might double as a watery grave.

Many old concrete pools are subject to heave or collapse without the counter force of water weight.