Gordon's Bay is a hidden Gem in Sydney, although it get's quite busy on weekends, it is hidden from the general public and A LOT of Sydney-siders have no idea it exists!
It is a beach/bay cut into the rocks between Coogee and Bronte with crystal clear water, sea-life and a relaxing/fun vibe. You will commonly find people playing music and floating around in blow up pool rings or similar.
It is a great place to float around, do laps, or snorkel as it is very flat with no waves. The rocks surrounding it provide a great place to work on your tan.