Number 5 jettisons 25% of the Tardis in Castrovalva,
so not so big in old who as new.
But as seen in "The Doctors Wife" after all the Bedrooms are deleted* the Doctor can just create more rooms.
IIRC the swimming pool was one of the rooms Doc#5 got rid of but we know he has that back again.
*Which probably meant Amy and Rory were down to one outfit each as well. Probably not a good idea to bring anything too valuable onto the TARDIS or if you do don't leave it in your bedroom
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It was the Zero Room (not very big at all )
so not so big in old who as new.
But as seen in "The Doctors Wife" after all the Bedrooms are deleted* the Doctor can just create more rooms.
IIRC the swimming pool was one of the rooms Doc#5 got rid of but we know he has that back again.
*Which probably meant Amy and Rory were down to one outfit each as well. Probably not a good idea to bring anything too valuable onto the TARDIS or if you do don't leave it in your bedroom
I think the 25% included the Zero Room, rather than just being the Zero Room alone.