Some ideas so far

Seasonal River Pool, idea by Urbis
This image depicts an Olympic standard pool floating in the Brisbane River.
Frog's Hollow Civic Space, idea by FORM
Brisbane City Super Canopy, idea by Urbis
Subterrain, idea by Andrea Goodwin, Creative Road Art Projects
Seasonal River Pool, idea by Urbis
Gabba Plaza, idea by CUSP
Green the Queen, idea by ARIA/Urbis