I grew up in Miami so it's a toss up between the Venetian Pool in Coral Gables:
and Matheson Hammock, a man-made atoll that looking south towards miles of protected undeveloped shoreline looks like the South Pacific:
And this aerial photo shows the developed coastline north of Matheson Hammock - the Miami most of you know, that unbridled waterfront development stretching non-stop north to Fort Lauderdale, Boca and beyond.
Even from its parking lot are astounding north facing views of the downtown Miami skyline and Key Biscayne, as well as from the sandbars in the open bay I'd walk as a kid. With my suit ON.
Since the thread started spamming international
photos I'll throw in these from my favorite foreign pool that I've actually visited, the calcium wading pools of Pamukkale, Turkey:
which project from cliffs, the tops of which are set some of the most amazing and archeologically significant ruins I've ever seen - Hieropolis - which has among other things multicolored hot springs (1st pic), a Jewish cemetery (2nd) and a Greek ampitheatre with a rare intact literal fourth wall (3rd):
So after getting your geology on at the pool you can get your archeology on at the ruins.